Fluttershy chewed daintily on her salad, the mare’s eyes fluttering closed as she reveled in the flavor. The texture, the taste, it was all so perfect, and combined with the gentle mid-afternoon breeze it made for a wonderful afternoon. That was until Rainbow Dash groaned from across the table, the other pegasus muttering some complaint under her breath.

Fluttershy sighed, and opened her eyes, glancing at her irritated friend sitting close by. Unlike Fluttershy, Rainbow Dash’s saddle bags were not beginning to fill with supplies and were mostly empty. While Fluttershy’s were starting to weigh her down, Rainbow Dash had not purchased anything that wasn't a snack or a wonder bolt poster.

“Did you say something, Rainbow Dash?” Fluttershy inquired.

“Yeah, I said this was boring,” Rainbow Dash exclaimed. “This restaurant is nice and all, but could you eat any slower?”

Fluttershy sighed and put down her fork. “You didn't have to come,” she pointed out. “I told you this wasn't going to be that interesting. All I’m doing is picking up a few things for my animals, and doing a bit of running around.”

“Yeah, but I didn't think it would be this boring. You’ve been eating that salad for like, eleven minutes and forty seconds already,” Rainbow Dash declared.

“Have you been… counting?” Fluttershy asked.

“It's not like I have anything better to do,” Rainbow Dash muttered.

Fluttershy ran a hoof down her face. “You can just leave if you like. You don't have to stay here. I didn't even think you would want to come, which is why I didn't invite you at first.”

“Yeah well, I was planning on saving this for later, but I guess our afternoon needs a bit more spicing up,” Rainbow Dash remarked before digging through her bags.

“What are you talking about?” Fluttershy questioned.

“This!” Rainbow Dash proclaimed, a small pink vial held aloft in her hoof.

“And what is that, exactly?” Fluttershy pressed.

“You’ll see in a second,” Rainbow Dash replied.

The speedster then uncorked the bottle, tipped its contents into her mouth, and swallowed hard. She then licked her lips, and tossed the empty container back into her bags, before belching loudly.

“That was actually kinda good. I’ll have to ask Zecora what she put in that one,” Rainbow Dash murmured.

“So… what exactly did you drink?” Fluttershy inquired.

“Wait a minute,” Rainbow Dash stalled, holding up a hoof. “Almost there, give it a second.”

Fluttershy sat there quietly while Rainbow Dash shifted around in her seat like she had to pee but was holding it in. After nearly three minutes of silence, Fluttershy was ready to ask again, only for Rainbow Dash’s face to light up.

“There! Give a look,” Rainbow Dash finally answered, pointing down at the table.

“Um, what am I looking for?”

“Not on the table, under it. Just trust me,” Rainbow Dash exclaimed.

Fluttershy shrugged and did as she was asked, kneeling down and looking beneath the table. Initially, she was confused as to what she was looking for as there was only the wooden table legs and the odd discarded piece of gum. Then she glanced up, her gaze landing upon Rainbow Dash’s crotch, and the teal erection sticking straight up into the air.

Standing at just a little shorter than the average stallion, the cock was about as thick as most. Where it lacked in dimensions it made up for in production, with pre cum already dribbling from its tip. The pair of balls that dangled under it was also visible twitching, churning with seed.

In an instant, Fluttershy was back above the table, a wide look of shock on her face.

“It's bigger,” she whispered. “How did you do that?”

“The potion, duh,” Rainbow Dash replied. “And it's only going to get bigger and more noticeable from here unless someone helps me with it.”

“Hold on. Is it permanent? How big will it get?” Fluttershy inquired, a blush springing to her cheeks.

“Big enough to stretch that tight asshole of yours in all the ways you love,” Rainbow Dash answered.

“Rainbow Dash,” Fluttershy hissed. “Were in the middle of a restaurant. We can't do that, and I have a bunch more stuff planned that I need to get done before we can go back to Ponyville.”

“Don't worry about it,” Rainbow Dash dismissed. “I can be done in no time flat, you know that.”

Fluttershy bit her lip and looked around the mostly empty restaurant. Placed on a rather large cloud near the edge of Cloudsdale, it had a scenic view, great food, and inattentive wait staff. The bathroom was also empty, the door to which was open just enough that Fluttershy could see inside.

“Come on,” Rainbow Dash pressed. “You’ve been hot and bothered ever since I asked how things went with Rarity.”

“I just modeled for her, that's all,” Fluttershy muttered.

“Yeah sure. You just walked around a bunch. That's why you were blushing for twenty minutes after and hobbled around a bunch because your back legs were pressed together,” Rainbow Dash retorted.

“Okay so it might have gotten a bit steamy,” Fluttershy admitted.

“That was more than a little steamy. I caught you eying my dick nearly every chance you got after I just mentioned Rarity,” Rainbow Dash continued.

Fluttershy blushed. “Well, I uh…”

“Come on,” Rainbow Dash repeated. “Just say yes, and we can go have a quickie in the bathroom. We’ve fucked nearly constantly since our teens. This is just like all those other times.”

Fluttershy bit her lip even harder, and though she wanted to say no, she was already sopping wet. Worse still, her asshole clenched down, the mare already remembering the many, many times Rainbow Dash had been inside of her. The horny brash pegasus wasn't very big and had a hair trigger, but she was fast and didn't seem to have a refractory period at all.

Just taking a trip down memory lane was enough to make a moan threaten to spill from Fluttershy’s lips. Thinking back on her more recent experiences with Rarity and Twilight only increased her arousal even more. Within mere moments a white-hot storm of lust burnt hot in her chest, leaving her tingling, and yearning for more.

“Okay,” Fluttershy whispered.

Rainbow Dash blinked, the shock quickly draining from her face and being replaced by excitement.

“That's what I’m talking about, now go into the bathroom and wait for a little bit. I’ll join you in a second,” Rainbow Dash commanded, gesturing to the open door waiting for her a few feet away.

Fluttershy hesitantly stood up from her chair and hobbled awkwardly towards the bathroom, tail tucked between her legs. Despite hiding her shame from sight, Fluttershy could tell that her friend was watching her closely. No doubt her gaze was crawling across Fluttershy’s jiggling backside, devouring the delectable sight before her.

Though such a thought would have made Fluttershy uncomfortable a few days ago, now it only excited her. She knew Rainbow Dash lusted after her, but to have others do the same, and so earnestly made Fluttershy feel… strange. Like waking up from a dream, Fluttershy was truly embracing her inner sexuality, rather than pushing it away.

Slipping inside the small room, Fluttershy busied herself by looking around. The space seemed normal enough at first glance. A toilet, a sink, a cute little end table with a few well-worn books mostly containing jokes, or simple wisdoms. It, like the rest of the restaurant, had an older, more rounded feel, and was a mix of white, red, and a bit of gold.

Her assessment of the place was interrupted after only a few short minutes, with Rainbow Dash entering the bathroom. The pegasus was quick to slide in through the narrow gap of the door, closing it shut behind her and locking it tightly. An excited grin was already on the pegasus’ face when she turned around and leaned in close.

“Are ya ready for a little fun, Fluttershy?” Rainbow Dash whispered.

“Mmhmm,” Fluttershy replied, bobbing her head.

“Alright, remember. Don't hold anything back. It's going to be quick,” Rainbow Dash exclaimed.

“Okay,” Fluttershy agreed.

“Great, put your forehooves up on that sink,” Rainbow Dash advised.

Fluttershy did as she was told, putting her front limbs on the cold porcelain, and spreading her back legs. Standing there with her head down, Fluttershy expected to feel Rainbow Dash’s familiar weight pressing down against her. That didn't happen, at least not initially, and Fluttershy looked up to find that her friend was staring at her ass.

The lust on her face was brazen and naked, the brash pegasus licking her lips with anticipation. Then, just as Fluttershy was about to ask what Rainbow Dash had planned, the other mare reared up. Her forehooves settled on Fluttershy’s hips, while her cock head expertly landed against Fluttershy's ass.

Rainbow Dash needed no lube, the pony merely thrusting a few times and spurting a considerable amount of pre. This was enough to allow the horny speedster entry to Fluttershy’s hole, the frequently abused orifice swallowing the futa cock with ease. A subtle change in Rainbow Dash’s grip was all she needed to get the right angle to really drill into Fluttershy.

Which she did so with gusto, squeezing Fluttershy’s thighs before plunging herself forward. Immediately her hips were a blur of motion, the pegasus jackhammering the other mare’s asshole. While she did this, Rainbow Dash stared into Fluttershy’s eyes in the mirror, a wide grin plastered firmly to her face.

It was almost intimidating how intensely Rainbow Dash looked at her, but Fluttershy did not qual from the sight of her friend. Instead, she met her gaze, albeit partially, through the strands of her mane. This only seemed to turn Rainbow Dash on, even more, the pony snorting and really putting her back into it. This resulted in the wet thwap of their hips meeting becoming louder than Rainbow Dash’s occasional grunt, and Fluttershy’s whispered moans.

“Y-you're too l-loud,” Fluttershy murmured.

“Don't worry. I got it,” Rainbow Dash extended a wing and flicked on the fan.

The resulting whir was enough to cover the sound of their almost violent copulation quite effectively. Rainbow Dash didn't even slow down, continuing to pound away with relentless, unthinking abandon. A pace that Fluttershy was becoming increasingly okay with, given that all of her recent partners took to it at least a little.

For a while, they remained there, with Fluttershy’s asshole continuing to get pounded by her lifelong friend. Though not the biggest cock ever, Rainbow Dash never let up, not even for a second, pushing herself to go faster than anyone else was capable of. The result was a surprisingly enjoyable experience that steadily got better, and better as time passed.

Within only a few minutes, Fluttershy was nearing her first orgasm, as was Rainbow Dash as well given how tight-lipped she had become. The speedster then reached forward and grabbed a hoof full of Fluttershy’s hair, pulling it backward. The move sent a bolt of pleasure down Fluttershy’s spine, and she couldn't help but release a soft cry of ecstasy.

It was mere seconds later when the speedster lurched to a stop, burying herself in Fluttershy’s asshole. Rainbow Dash barely even made a sound as she came, merely biting down on her lip and only letting the odd grunt escape. Fluttershy however, was an expert on being quiet, and her moan came out barely above a whisper.

Together the two mares shared a short, but powerful orgasm together. A few seconds later, it was over, and Rainbow Dash collapsed against her friend’s back, a wide grin on her face.

“That was fun. I’m already looking forward to next time,” Rainbow Dash offered.

“Me too,” Fluttershy murmured.

“Great, let's get cleaned up and head out then,” Rainbow Dash exclaimed.

“Wait,” Fluttershy interrupted. “What about um, your stuff? Won't I make a mess?”

“I got ya covered,” RainbowDash replied.

The pegasus then leaned back, and gripped something, removing it with a slight tug followed by a pop then a long slurp. A moment later she revealed that she was holding a surprisingly large butt plug with a wide base, and then a long bendy part over a foot long. Colored the same shade of blue as Rainbow Dash’s fur, the toy was a truly remarkable length and girth.

“Were you just… walking around with that?” Fluttershy muttered.

“All day,” Rainbow Dash answered with a grin. “Now hold on a sec.”

Fluttershy couldn't even get a word in edgewise before Rainbow Dash pulled out of her and swiftly inserted the end of the plug. A single, firm shove of her hoof rammed the thing deep into the shy mare’s backside, burying itself deep into her body. In an instant Fluttershy went from feeling empty, to completely and utterly full.

“Oh, oh my,” Fluttershy murmured.

“And we didn't even spill a drop,” Rainbow Dash declared, slapping Fluttershy’s backside. “Come on. You got stuff to do, right?”

“Er um, yes,” Fluttershy murmured.

“Great. I’ll go get the bill while you clean yourself up,” Rainbow Dash took a step away only to pause and turn back around, planting a kiss on Fluttershy’s cheek. “Oh and thanks. You’re the best, Fluttershy.”

The speedster then quickly departed, leaving a flustered and flushed Fluttershy to stand there awkwardly.

“Oh my,” she murmured, hoof brushing her cheek.

“Hmm, I could really use a new cage for injured animals, but which one?” Fluttershy murmured to herself.

Rainbow Dash stood beside her friend, looking bored, the pony using her time to glance about the store. Large, old, and operated by an ancient mare sitting nearly thirty feet away behind several rows of items, there wasn't much to look at. Only a seemingly endless supply of pet-related stuff, from simple food to enormous cages big enough to fit an adult bear inside. There at the back end of the store, the pair was almost completely shrouded in darkness, with the lights flickering above their heads.

“Hey, Fluttershy. Wanna go another round?” Rainbow Dash asked casually.

“But we just did it a few minutes ago in the alley,” Fluttershy whispered, a hoof going to her stomach. “I don't know how many more of your loads I can fit inside of me.”

“Oh come on. You can take, and besides. You want it, don't you?” Rainbow Dash teased.

“Well…” Fluttershy whispered absently.

“I can tell you do,” Rainbow Dash teased. “Besides, it's gotten even bigger, you know.”

Rainbow Dash lifted her back leg and displayed her cock for all to see, proving that it was indeed larger. Thicker, longer, the heavy appendage was as big as Twilight had been a few days earlier. That thought, that connection sent a fresh wave of arousal trickling down Fluttershy’s legs and she couldn't help but grin.

“See? What I tell ya. So I’ll just sit down on the floor and you can ride me right here,” Rainbow Dash explained.

“Wh-what?” Fluttershy gasped. “We can't do it right here. What about Mrs’ Apple Bottom?”

“She's nearsighted, and probably hasn't left that desk since the Wind Socks won the buckball championship in ‘92,” Rainbow Dash retorted.

“Come on, if you go quick it will be over in only a few minutes,” Rainbow Dash continued.

As Fluttershy struggled to make up her mind, Rainbow Dash plunked down on the ground. Her cock sticking straight up in the air, the pony flashed the other mare a grin. That was all it took to force a decision on Fluttershy, and she trotted over to her friend, ass clapping gently as she moved.

“You know from down here I think your butt has gotten even bigger,” Rainbow Dash remarked.

Fluttershy paused, and looked back, grabbing her ass with a hoof and giving it a squeeze.

“I… think it is,” Fluttershy admitted.

“Probably a bit of the potion remaining in my cum, and making your butt even phatter,” Rainbow Dash theorized. “Anyway, let's go already. You don't want Mrs’ Pear Butt to catch us, do you?”

Fluttershy hesitated a moment before trotting straddling her friend, legs spread wide and ass hovering over Rainbow Dash’s cock. Fluttershy paused, reaching back and with a surprising amount of difficulty, arced a hoof around her ass. Once she had plucked the toy from her hole, she placed it nearby and clenched, holding in all the cum pumped into her.

A subtle adjustment later and Fluttershy was now gripping a large animal cage with her forehooves while lowering herself down. With expert precision and a bit of help from her partner, Fluttershy landed exactly where she was aiming, impaling herself on the other pony’s throbbing erection. Though larger than before, it was nothing Fluttershy couldn't handle, especially after spending so long with a toy inside of her.

The sensation of fullness returned, washing away the discomfort of no longer having something inside of her. She didn't stay there, relishing the sensation for long, however, and quickly began to bounce her hips up and down. As she did so, she occasionally glanced through the cage, and over to where the proprietor sat, impassive with a book held in front of her.

Fluttershy was distracted from her peeping by Rainbow Dash suddenly grabbing her ass cheeks and squeezing. The speedster hungrily kneaded Fluttershy’s massive butt, drawing forth another moan from the shy mare. A moan which she stuffed down deep inside of herself, focusing entirely on riding Rainbow Dash’s cock.

Up and down she went, lip bit and hooves gripping tightly on the cage. Below her, Rainbow Dash continued to squeeze and molest the other pony’s butt. While also grunting on occasion, or nipping at Fluttershy’s neck whenever she got in range.

Though she did her best to ignore her friend’s teasing, Fluttershy couldn't help but giggle. The passion remained, as did her own burning lust, but there was also a casualness to the encounter. They had known each other forever and had done it enough times that it wasn't quite so serious.

Both of them knew that they were rushing towards orgasm and weren't holding back in the slightest. At least for the most part, as they contained the sound of their pleasure, leaving only the heavy slap of flesh meeting flesh. There was nothing they could do about that, as Fluttershy’s butt was simply too large to properly stifle.

“I’m close,” Fluttershy whispered not long after they had begun.

“Me too,” Rainbow Dash replied.

Both of them held on a little tighter, as Fluttershy moved as swiftly as she dared. For several tense moments, there was only the dull slap of flesh meeting before Rainbow Dash grunted. This was all the sign Fluttershy needed, the pony dropping her hips one final time. Impaled as deep as physically possible, Fluttershy could feel Rainbow Dash’s load as it was pumped inside of her by the futa mare’s veiny appendage.

The rhythmic pulse of her cock depositing its load into her guts elevated Fluttershy’s orgasm even higher. The slight slurping noise as the rest of her friend’s cum shifted around inside of her was also a weirdly arousing sound. As was the small, but noticeable paunch that she was now sporting due to the sheer volume of cum sitting inside of her.

“Fuck that's hot,” Rainbow Dash whispered, a hoof caressing her friend’s belly.

“Yeah, it's kind of-” Fluttershy began.

“Are you alright back their dear?” asked a voice.

Fluttershy’s eyes went wide, and she pulled herself up on shaky hooves, careful to not remove the cock from her ass. She didn't want to even imagine how big the mess that would have made if that happened. Peering through the cage she found that Mrs. Applebottom was approaching her, a curious look on the other female’s face.

“Oh just fine. I uh… fell. Rainbow Dash is just helping me up,” Fluttershy replied.

“Uh yeah. Totally!” Rainbow Dash added.

The speedster grabbed the toy and deftly inserted it into Fluttershy’s asshole while pulling her cock from the other mare’s depths.

“Are you sure? You sound winded,” Mrs. Applebottom continued.

The owner turned the final corner just as Rainbow Dash leaped to her hooves, and Fluttershy turned towards the pet store owner

“Everything’s perfectly all right now. We're fine, we're all fine here now thank you,” Fluttershy blubbered. “How are you?”

Mrs. Applebottom stood there for several seconds, looking up and down at the two other ponies before finally releasing a sigh.

“Terrible,” she exclaimed. “You would not believe how awful business is these days. I swear that new chain opening up across town is stealing all my business.”

“Oh, uh. Really?” Fluttershy pressed.

Mrs. Applebottom shook her head. “You have no idea. Why just the other day-”

While the older pony began to rant, Rainbow Dash leaned a little closer and planted a kiss on Fluttershy’s cheek. While she did this, the speedster also made sure to grab her friend’s butt and give it a firm squeeze.

“That was great. I can't wait to do it again,” Rainbow Dash whispered.

“Me neither,” Fluttershy replied, a soft smile coming to her face.

Fluttershy grunted, tugging on the warm summer sun dress she was attempting to put on. Though it fit most of her just fine, it was struggling to fit around her now-massive posterior. In fact, her butt was now so large that it had been difficult to get into the narrow changing room in the first place.

With a huff, Fluttershy gave up, letting the piece of cloth hang over her body loosely, ending just before her flanks. Which were round, and extended from her sides several inches, making it impossible to walk without a soft clap accompanying every step. Worse still, Fluttershy could no longer reach the toy jammed inside of her, not like she wanted to, mind you.

With nearly a dozen of Rainbow Dash’s loads sitting inside her belly, Fluttershy worried about the mess that might cause. A concern that reared its head when she brushed a hoof against the bulge in her midsection and caused its contents to gently slosh inside of her. The sensation of so much of her friend’s jizz shifting around inside of her made Fluttershy become aroused all over again.

She tried to ignore the sensation, to push down her building lust but it burned on anyway. It was so powerful in fact, that Fluttershy peeked out of the changing room, and searched for Rainbow Dash. Who she found only a few feet away, sitting on a waiting chair, her head drooping as she struggled to stay awake.

“Pssst, Rainbow Dash,” Fluttershy whispered, careful to not alert the distant sales ponies helping others across the store. “Over here.”

Rainbow Dash perked up, a smile coming to her face. “Oh hey Fluttershy. You ready to blow this popsicle stand?”

“Oh um, not quite yet. I was wondering if you could help me with something,” Fluttershy continued.

“Sure. What do you need?” Rainbow Dash replied.

“I um. Need some assistance putting on this dress,” Fluttershy murmured, a blush crossing her face.

“A dress, really?” Rainbow Dash deadpanned.

“Yes,” hissed Fluttershy.

“Alright,” Rainbow Dash muttered.

The brash pegasus stepped forward and slipped through the narrow door, or at least she tried to anyway. As she got just barely inside before nearly being crushed against the wall by Fluttershy’s huge ass.

“Holy crap,” Rainbow Dash exclaimed in shock.

“Oh um, sorry,” Fluttershy murmured.

Rainbow Dash grinned. “Damn girl. You are even hornier than me, and that's saying something.”

“I just… couldn't wait anymore,” Fluttershy murmured.

Rainbow Dash grinned, the pony taking a moment to adjust herself, shifting her back legs around. Pressed between her friend’s ass, and the wall, Rainbow Dash was barely able to pull the door closed behind her. Once she did, the speedster took a moment to appreciate the view waiting right in front of her face.

“How am I even going to get inside of you? There's barely any room in here,” Rainbow Dash pointed out.

“Just um, give me a second,” Fluttershy murmured.

The shy pegasus put her hooves over her head and shuffled as close as she could manage to the wall. This gave Rainbow Dash just enough room to pull out her cock, and place it in the cleft of Fluttershy’s butt. There it rested, the surprisingly long, heavy appendage managing to fill up the cavernous space between the shy mare’s ass cheeks.

“You’re so big,” Fluttershy murmured.

Rainbow Dash grinned and ran a hoof down her length. “It's thicker than my hoof and nearly as long as my leg. I bet even a butt slut like you is going to struggle with something this big.”

“Oh um, maybe,” Fluttershy murmured, a blush burning hotly on her cheeks.

“Well let's jam it in you and see. My balls are starting to ache they are so heavy,” Rainbow Dash remarked.

Pulling her hips back, Rainbow Dash angled her cock towards Fluttershy’s asshole with considerable effort. The angles were weird and required more bending than the speedster was used to, but it wasn't anything she couldn't handle. A bit of flexibility was required to be a wonderbolt, after all, she just needed to push herself a little bit.

In no time at all, she had nearly lined herself up with her prize, and only a single obstacle lay before her. Gripping the rubber end of the dildo plug, Rainbow Dash gently pulled, the thing sliding out almost immediately. Then, like Daring Do switching an ancient idol for a bag of sand, Rainbow Dash deftly slid her cock inside Fluttershy as the toy was removed.

With expert precision she replaced the fake dick with a real one, plugging Fluttershy’s hole before any cum could leak out. A process that quickly became more difficult, as even with all the natural lube, Rainbow Dash was still too big. Her fifth leg had truly grown into the phrase, the appendage stretching Fluttershy to her absolute limit.

“Stars above Rainbow Dash,” Fluttershy murmured huskily. “You’re huge.”

“Still think you can take it all?” Rainbow Dash asked.

“I’ll make it fit,” Fluttershy declared.

Rainbow Dash grinned. “That's what I like to hear. Let's do this!”

Rainbow Dash punctuated her declaration by thrusting her hips forward, burying a good third of her length into the other mare. Who moaned loudly, her hooves pressing against the full-length mirror with enough force to almost make it crack. Driven on by Fluttershy’s clear arousal, Rainbow Dash pushed on, pounding forward repeatedly.

Tight, and barely able to take her, Fluttershy’s asshole was forced to stretch further than ever before. And the mare herself loved every last second of mind-blowing pleasure, and incredible stretching. It almost felt like her body was being molded by that monster cock, made into a vessel for it alone.

Then all too soon it was over, and Rainbow Dash had bottomed out.

Fluttershy lay with her face against the glass, breathing heavily as she struggled to handle all the lust burning inside of her. The depth, the way her ass spread, the weight of cum already inside of her, it was all so perfect. That was until Rainbow Dash began to move, then Fluttershy realized what true perfection truly felt like.

The tight confines of the changing room barely left any space to move, but that was enough for the athletic pony. With earth-shattering thrusts, she pounded her hips against Fluttershy’s, the impact making her huge ass cheeks jiggle. The rippling, undulating flesh was gripped tightly by Rainbow Dash as she continually threw herself forward.

In under a second, she had reached her usual rapid, jackhammer-like pace, her hips becoming a blur of motion. Leaving Fluttershy scrambling to respond, a hoof immediately going to her slightly sloshing stomach in hopes of quieting it. This only half worked and did nothing about the clap of her ass cheeks, but there wasn't anything she could do about that.

Save to hope against hope that no one heard them over the soft music piped into the store from unseen speakers.

Rainbow Dash clearly didn't care, the pony throwing herself into the act with all the strength she could muster. Like every other time that day, she never slowed down, never gave an inch, and simply rushed to her next orgasm. Fluttershy’s worries that they might be going a bit too fast vanished almost immediately, as her own orgasm was swiftly approaching.

A mere minute in and she could already feel it edging to the precipice of release. She held on though, gripping the wall in one hoof and her belly in the other while looking back at Rainbow Dash in the reflection. The speedster grinned with uncontainable excitement, pride leaking out of the corner of her smile.

“You are the most beautiful mare in the world, Fluttershy,” Rainbow Dash whispered. “I’m one lucky pegasus to know you.”

Fluttershy wanted to say thank you, or possibly return the compliment with one of her own but she couldn't find her voice. The pleasure and embarrassment were simply too much for the shy pony who smiled and gave her friend an appreciative nod back.

“Right, let's really fill this ass!” Rainbow Dash exclaimed.

Before Fluttershy had a chance to respond, Rainbow Dash’s grip tightened, squeezing the shy pony’s ass tightly. She then did the unthinkable and somehow began moving even faster, her hips reaching a speed Fluttershy did not think possible. It was all Fluttershy had to keep her legs from going numb, and collapsing to the ground while her asshole was brutalized.

A few seconds of resisting her own orgasm and the dam broke, and Fluttershy came so hard she saw stars. Keeping the cry of ecstasy from exploding out of her mouth was a near-impossible task. Yet Fluttershy managed to do so, the sound slipping out of her clenched lips as barely more than a whisper.

Rainbow Dash, however, had slightly less restraint. The speedster released a long throaty moan of pleasure while thrusting messily into her friend’s ass. Like Fluttershy, Rainbow Dash was so overwhelmed with pleasure that she could barely keep it together. Her thrusts became sporadic, and soon she jerked awkwardly to a stop, her hips flush against her friend’s.

There they remained, with Rainbow Dash’s body as rigid as a board while Fluttershy trembled, barely able to stand. Seconds ticked by as cum erupted into Fluttershy’s depths, her stomach gurgling as futa seed flooded her insides. This final eruption was the most powerful Fluttershy had ever felt, and it was almost like she had a firehose jammed into her backside.

Then it stopped, and Rainbow Dash collapsed against Fluttershy’s back, a low sigh escaping her lips.

“Fuck that was good,” Rainbow Dash muttered.

“Oh um, yes. Very,” Fluttershy replied.

A hoof banging on the door made both mares go rigid in shock.

“Hey, are you almost done in there?” barked an angry male voice.

“Yeah, just a sec!” Rainbow Dash shouted.

“Just hurry up already. I got a whole line of customers waiting,” replied the voice.

“I will!” Rainbow Dash added.

“Oh and clean up after yourself! Ya damn, kids,” muttered the voice.

“Did he figure us out?” Fluttershy murmured.

“I think he did,” Rainbow Dash replied.

“Oh... Oh my,” Fluttershy whispered.

“Eh I wouldn't worry about it,” Rainbow Dash exclaimed. “If he was going to get us in trouble he would have done so already.”

“Still,” Fluttershy glanced in the mirror. “Oh wow. I don't know if we’ll be able to get out of here. My butt is just… so big.”

“Eh it should only last another minute or so,” Rainbow Dash explained. “Then we should both return to normal.”

“Oh.”

“Heh, you almost seem disappointed,” Rainbow Dash teased, prodding the other mare’s shoulder. “Don't tell me someone likes having a huge cock jammed up their equally as massive butt?”

“Well um, kind of,” Fluttershy reluctantly admitted.

“Pfft, come on. Did you really think I’d only bring one vial with me?” Rainbow Dash exclaimed.

Fluttershy looked back to her cocky, smirking friend, who held in her hoof nearly a dozen of those same small glass containers. Inside of which rested more than enough of the delicious, ass-expanding, cock growing liquid to make their entire day a pleasurable one.

No, Fluttershy realized, it was enough to make her entire week.

The shy pony grinned.

Author's Note

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