The walls of Sugarcube Corner shook as Rainbow Dash howled.
“Oh come on, Dashie,” Pinkie Pie cooed as she leaned forward, nipping playfully at one of Rainbow Dash’s ears. She wiggled her hips, earning another groan from Dash. “I’m only halfway in.”
Rainbow Dash turned back to stare up at Pinkie Pie, eyes wide open. “H-half?” she whimpered, her strong voice reduced to a whimper. Pinned against Pinkie’s bed, she couldn’t do much more than stare in horror as she turned her gaze down past her own hips to what Pinkie Pie had wedged firmly into her backside. She whimpered.
A pair of pendulous pink balls rested atop the comforter, Pinkie Pie’s bloated sack filling up the space between her legs so much that she had to keep them spread apart just to make room for their mass. It was mind-numbing, trying to wrap her head around just how large they were. Nothing in Rainbow Dash’s life had prepared her for how large Pinkie Pie’s testicles could be.
They had nothing on the cock attached to them, however. When Pinkie Pie had first revealed herself to Rainbow, she’d been excited by the size, her friend sporting a dick big enough to put any stallion she’d seen to shame. But then it had started growing bigger, filling up the space beneath Pinkie’s barrel as she told an increasingly incredulous Dash that she was just getting hard.
That had only been a few minutes ago. Everything seemed to pass in a haze as Rainbow had been led to Pinkie’s bed, climbing up onto it as Pinkie continued to stroke her erection, urging it to reach its full size. And now Pinkie’s cock, like her ballsack, defied reality. It was as thick as the mare’s waist and stuck out from between her arms, large enough to intimidate a horny dragon, let alone a little blue pegasus.
Or it had stuck out that far before she’d lifted Rainbow’s tail and shoved herself as hard as she could inside her friend. It hadn’t taken long for Pinkie Pie to start pushing deeper, and Rainbow could feel her malleable body deforming around Pinkie Pie’s insistent insertion.
“Jeeze! You gotta pull out, Pinkie. You’re too big,” Rainbow protested, wanting to pull away but unable to command her limbs to do anything. She turned her frightened gaze down to her belly. The outline of Pinkie’s cock had lost some of its definition as her stomach had expanded outwards, but the head was still clearly visible through her skin which was being forcefully pushed outwards. “Oh Celestia, how is this even possible? I look pregnant!”
"What? You look pregnant already?" Pinkie Pie asked, rubbing Rainbow Dash's bloated belly. She started laughing, making no move to pull her cock from Dash's aching cunt as she giggled happily. "Well that's not a good sign, now is it? I mean, that's just my pre. If you're going to be a real cumdumpster like you said you could be, then you'll have to take more than that. Much more."
Rainbow Dash just looked down at her stomach in shock, the gravid swell of her middle only marred by the obvious bump of Pinkie Pie's physics-defying dick half-way up her torso. "Wha- P-pre!? That... that... How?" she finally gasped. "When I said I could take anything you could give, I didn’t know… you weren’t this big! This is… this is just impossible!"
"Naw, this is just part of being a Pie. We’re pretty tough and strong and got pleeeeenty of stamina. You've met my sister and seen what she could do." She ran a hoof over that swollen gut, rubbing her own cock through the skin before she began thrusting slowly again. "Hehe... It's funny, Dashie. You're normally so cool and fast... but right now, you're nothing more than a tiny little cock-sock for me." Pinkie Pie leaned forward. "Though, you should have seen what I did to my last plaything when I finally did cum. You'd better hope that after all your bragging, you can take more than Big Mac did..."
Rainbow Dash tried to protest, tried to beg for help, tried to do a dozen different things at once, but instead, as Pinkie Pie bucked her hips forward and drove that barrel-thick cock up into her straining body, all she could do was moan even louder. She was terrified, scared out of her mind... yet it still felt so good. Incredible, even. Her fantasies had never reached this level of absurdity, yet now that it was happening, her body was betraying her, enjoying every sensation of being so brutally stretched over her former-friend's monster dick, even as she worried what those enormous testicles would do to her when they finally released their load. If Pinkie Pie's pre was enough to leave her looking pregnant... Rainbow’s moans turned to whimpers as she realized Pinkie Pie's room might not be big enough... if she even survived that long.
"Oh Rainbow, you're getting even tighter!" Pinkie Pie declared, laughing as she began to see-saw her cock in and out of Dash's straining cunt, watching the way her tree-trunk shaft deformed Rainbow Dash's belly, causing the slight cum-bulge there to sway and slosh with each motion. "Oh yeah, squeeze like that! Mmm... that makes my stallion thingy feel super good." Already Pinkie's dick was back in production, a steady stream of thick, virile precum adding to the liquid mess bloating out Dash.
Rainbow Dash moaned. "No, I don’t l-like it. It’s too big," she tried protesting, even as she rubbed that invading cock. She wanted to curse herself for having given in to her lust and accepting Pinkie’s offer, but as frightened as she was, her mind was assaulted with the physical joy of being stuffed so full.
"Oh come on, you said that before, and right now you're still squeezing back like you want more. I knew you'd like being my cum dumpster. It suits you. As soon as I told you about my little secret and how even Applejack couldn’t handle me, you were just gushing. But now, even though you know my true size, you still want me to fuck you bigger! And gosh, as your best friend, I don't think I can turn you down." Her grin turned predatory as she squeezed Dash's ass. "Let's just hope you hold more than that mare from Canterlot who went 'missing' last month. That was a real disappointment."
A cold sweat came over Rainbow as she heard those words, chilled to the bone despite the warmth of the cock she was impaled upon. "What mare? What happened?" she almost shouted, still trying to squirm away from Pinkie Pie as the bed creaked beneath them, but Pinkie Pie just shushed her.
"Don't worry, Rainbow. That won't happen to you. You told me you could take it all, even after I said I was pretty big. So I'm holding you to your word." She grinned and gave Rainbow's ass a smack. "I mean you're not the element of honesty, but I believe you just like I believed Applejack. And besides, you're a biiiig hero, so of course you can take a biiiig load. It's not like you were just making that up to get me to fuck you, right? That would be just silly, especially after I warned you that I'm pretty big and most ponies can't handle me." She thrust forward again, her heaving testicles slapping against the back of Rainbow's legs. "And I'm the silly pony, not you, Rainbow Dash."
"T-This doesn't feel very silly!" Rainbow shouted, unable to look away from the slowly expanding gut beneath her, feeling every squirt of Pinkie Pie's thick seed. She cursed how good it felt, the way her body seemed to try and sabotage her at every step. She knew she should try to escape, yet every time she made a move her body quivered or shook or pushed back against Pinkie Pie. Now she was stuck watching herself being slowly inflated by her friend's impossible cock. "Alright, I admit it! I can’t take as much as Applejack, okay? This is just too much!"
"Too much?" Pinkie Pie giggled as she began to increase her pace, the thwap-thwap of balls on flesh matching the thunk of the bed-frame hitting the wall, letting the whole house know what Pinkie Pie was doing in her room. "That's not too much. Not at all." She moved even faster, her cock starting to grow thicker as the tip flared wide. Rainbow's eyes shot open in alarm as she realized what was happening, but it was too late. "No, I'll show you what too much feels like!"
Throwing back her head Pinkie Pie let out a loud groan of pleasure as she shoved herself back into Dash's well-used cunt, sheathing her whole dick as her cum-slit yawned wide enough to swallow a whole hoof. Rainbow could feel Pinkie's seed traveling down her cock, bulging out the underside of her shaft before the first stream erupted from the head.
The first burst of cum was hard enough to knock the wind from Rainbow's lungs. Ropes of hot seed began pumping into her womb at an incredible rate, audibly sloshing around as her stomach exploded outwards, pushing firmly against the bed in mere moments. After less than a minute she could barely stand on her hooves. Another minute later and she was entirely supported by her belly. And still, Pinkie Pie continued to cum.
It was impossible. Physically impossible. But no matter how much Rainbow screamed it, Pinkie Pie's balls just continued to pull tight and force more hot cum into Dash’s expanding middle. The crack of the bed breaking apart was lost beneath their moans and the gushing of Pinkie's river of cum being directed straight into Rainbow's womb, leaving her a belly with a mare attached. And still, even as Rainbow heard her belly start to creak, her skin pulled as taut as a drum, there was always more cum, always more to fill her up.
All the while Pinkie Pie rubbed her head, cooing softly. "Oh yes Rainbow, yessss... Take it ah-all like a good little cum d-dumpster..."
The orgasm seemed endless as time lost its meaning, Rainbow Dash's entire world shrunk down to the cock embedded inside her and the way her stomach continued to expand outwards, crushing the bed's remains beneath her growing bulk until her bloated blue belly dominated the room, with Pinkie Pie perched atop her, continuing to pour more and more into her until it seemed she was going to just explode.
Eventually, though, it came to an end. Pinkie Pie let out a low growl and kissed Dash's neck hungrily as she gave a final thrust, forcing out a final stream the equal of a dozen stallions, before she relaxed and let half her cock withdraw from Rainbow's pussy. "Hehehe. Wow, I really needed that. It's been like, a week since I got any relief. I was super backed up," Pinkie Pie said, rubbing her hooves down Rainbow's sides, feeling the warmth of all her cum pushed deep into Dash's depths. She giggled. "And now I have a nice waterbed!"
"Gah... P-Pinkie... look at... me," Rainbow managed, panting heavily. Her insides felt bruised and battered from the streamers of ejaculate that left her looking more like a balloon than a pony. "I'm... I'm huge."
"Well, I'd say big, not huge. Or maybe just average. Cause this isn’t anything really special, you know?"
Rainbow Dash shook her head weakly. "Just... please, can you let me go now? I've... I've learned my lesson. I don't want to be your cumdumpster any... any more."
"Go?" Pinkie Pie cocked her head to the side. "Why would I let you go? I'm not done yet."
Rainbow Dash froze. Her eyes became pinpricks. "W-what?" she whispered, her hooves digging into her own belly, unable to even stand up anymore. She looked up at Pinkie Pie. "But... but you came. We're done... right?"
"I only came once, Dashie. That's like just getting started." She smiled, that dark, hungry smile. "I told you I've been feeling a bit backed up. I normally cum like this two or three times a day." She leaned closer. "And it's been a week since I last met a cute mare with a tight cunt who wanted to help me unload... so you've got a lot of work to do before we're done, Dashie-Dumpster! Now, go ahead and squeeze those thighs together, because I think I'm ready for round two!"
