Dinky Doo's Big Adventure

"What the fuck was that?"

Tiara lay prone on her back, chest rising and falling heavily. "I have no idea," she breathed in between pants, wiping a strand of cum – her cum – from her face. "But it felt awesome." She grinned, and shifted herself so that she was sitting, leaning against the mirrored wall for support.

"You grew a dick. That isn't fucking normal."

"You're one to talk," Tiara retorted, lazily gesturing her head at Dinky's own prodigious member.

Dinky blushed, averting her gaze. "We should probably call a doctor. Or something. Fuck, I dunno, this isn't-"

"Normal, you said." Silver gave Dinky's hair a light tousle. "You need to chill. Seriously."

"And anyway, it's not like we need a doctor to tell us what happened. You, little missy, are contagious." Tiara smirked, before turning her attention to her new meat. She looked it over appraisingly, giving it a little squeeze. "Not much to write home about. Yet." She licked her lips.

"W-well," Dinky stuttered, blushing slightly, "maybe it doesn't grow with sex. Maybe that's just me?" She was still pointedly avoiding looking at any of the other two penises in the room, though her eyes betrayed her, darting to gaze at Tiara's lavender shaft.

"Well," Tiara pushed herself to her feet. "There's one way to find out for certain. Twist." She pointed, and Twist grinned eagerly. "You're the only pony here without a cock of her own. Wanna try and see if we can fix that?"

"Oh, fuck yeth!" Twist eagerly manoeuvred herself onto all fours, wiggling her ample ass in the air. "Fuck me hard! Pump me full of your baby batter!"

"Ech, no talking." Tiara wrinkled her nose. "That was probably the most unsexy thing I've ever heard. Just... your mouth is put to better use giving Dinky a blowjob or something."

"No, thanks," Dinky grunted, scooting away. "I think I've had enough sex for one day."

"What, you don't wanna test out how this shit works? I mean, if this happened to me – and oh, look, it did – I know I'd sure as shit wanna spend some time figuring out the rules. If I fuck Twist in her cunt, will she grow a dick? What if I fuck her ass? What about Silver, will it make her cock start growing? Will she grow another cock? Does masturbation make it grow, too? Or does someone else have to be directly involved in the orgasm?" She firmly grasped Twist's ass with one hand, the other steadying her drooling shaft. "And, most importantly-" she thrust her cock into Twist's asshole, grunting from the tightness of her partner's hole. "How fuckin' big can we get? Oh, shit, your ass is fucking tight, slut.”

“I'm already too big,” Dinky muttered, trying not to stare as Tiara began to thrust in and out of Twist. “I don't wanna grow bigger, let alone push the fucking limits.” “You fucking lunatic,” she didn't add on to the end of her sentence, but the unspoken sentiment was there.

“There's – nggggg – there's no such thing as too biiiiig. Only t- fuck – too smallfuckyes!” She thrust hard into Twist, before resuming a more consistent rhythm to her relentless fucking. “And right now I'm waaaaay too fucking smaaaaaaaaAAAAAAA!” Tiara's regular rhythm became erratic – and much faster, plunging her length into Twist with relentless abandon. Each time she pulled out, cum spurted out with her, leaving her crotch increasingly coated in streaks of sticky white. And each thrust inward churned the cum into a bubbly froth. “Ooooh FUCK, I can feel it happening! Bigger! Bigger! Fucking BIGGER!”

Dinky's hands wandered southwards.

“Ngggg,” Tiara groaned as Twist slumped forward, tongue lolling out of her mouth giddily. Slowly, she pulled herself from within Twist, inch after inch. Almost certainly more inches than had initially gone in. “Fuck, that felt good. Got a dick, yet, Twist?”

“Noooooooo,” she groaned, writhing around on the ground. “But it tinglethhhhhhh.”

“Well, then,” Tiara grunted as she pushed herself to her feet. “Give it a bit to grow in, and if it doesn't I'll fuck your cunt once I'm done blowing Silver.”

Silver interlocked her fingers and stretched her arms above her head. “About damn time.” Her cock twitched, drooling pre in anticipation. “Might I enquire why I'm the one getting a blowjob?”

“Well,” Tiara lowered herself to her knees, and leaned in to give Silver's obsidian monolith a gentle caress, drawing a cooing noise from the taller mare. “I don't wanna fuck you properly just yet because then you might end up growing, and we can't have that until I've got a solid lead on you. Don't wanna risk not being the biggest, after all~” She gently kissed the head, licking up some of Silver's copious pre.

“Mng, that's fair. So then why am I not the one blowing you, oh mistress of mine?”

“Har. No need to be sarcastic.” Tiara gave Silver's member a rough squeeze, drawing a satisfying grunt. “I already know getting blown makes it grow. I wanna see if it'll grow if I'm the one doing the blowing.”

“Well, Dinky's only grows when she cums, and right now you're not getting any stimulation, sooo-”

“Woah hey what!” Silver lifted Tiara, elegantly suplexing her up and forward until she was sitting on her face. “What the fuck?!”

“Like I said, you aren't gonna cum if you don't get any stimulation. We already know you can get bigger if I suck you off, and that'd probably apply to a handie, too. But,” she reached upwards and adjusted Tiara's balls, pushing them forward and aside in order to get a better shot at her real prize. “There's other ways to show a lady a good time. Like, oh, for instance...” Her head darted forward, giving Tiara's clit a gentle nibble.

“G-haaaaaa fuckin'-” Tiara's ass came down on Silver's face, hard, enveloping her in soft, warm flesh. “Ahaaaaan god damn Silver I can't suck your coooOOOock while you're doing thaaaaAAAAA-” She squirmed, Silver's arms darting upwards to firmly hold her in place before she could thrust her way out of cunnilingus. Silver's talented tongue hit all of her most sensitive spots, leaving her writhing with pleasure on the edge of orgasm. “Silver this isn't funnyyyyyy!” Tiara convulsed as Silver relentlessly ate her out, her back arching and her hips quivering as they impotently attempted to out-thrust the much larger mare's iron grip – and even then, her legs had just enough wiggle room to kick out wildly and erratically. Her arms splayed out on the floor, rigid and quivering and just barely keeping her body upright. “Gonna cuuuummmmm~ Gonna get bigerrrrrrrrr~ Gonna get huuuuuuge~ Gonna- gonna- gonna- goooohfuck!” Tiara's upper body strength gave out, and her body slowly slid down until her head gently reached the ground, arms splayed to her sides and face down, body mostly parallel with Silver.

And then, just like that, it all stopped. Tiara slumped forward limply as Silver released her grip. “Oh, come the fuck on! You know I fucking hate being edged, Silver!” She groaned, writhing against the ground. “That's my job!”

“Oh, don't worry, it's gonna be worth it, I promise.” Silver grasped Tiara's hips, hefting her ample ass in the air. Her thumbs deftly parted Tiara's cheeks, revealing drooling lower lips just begging to get fucked senseless. “I figured you'd get pissed at me if I stuck to oral. 'n anyway, I've only came once so far and you're already pushing three.” She entered Tiara with the ease of a seasoned expert.

Tiara cooed. “Mngggggg yeah, fuuuuck, I approve of this decision~” She made a feeble attempt to push her upper body off of the ground, failing miserably. All of her strength had been sapped by Silver's earlier attentions, her arms just managing to twitch halfheartedly in time with Silver's slow, methodical thrusts. “Ahnnnnn, Silver, you bitch, fuck me harder!”

“Nnnnnope.” Silver grinned, giving Tiara's ass a nice, firm slap. “Way I see it, you're almost certainly gonna let Little Tiara go to your head. This might very well be the last time I get to make you my bitch for a good long while and I intend to enjoy myself~”

“Gnnnnn, fuck you.”

“That comes later, babe. Fuck, you're tight.” Silver didn't have to take it slowly. She could, and very often did, jump right to burying herself to the hilt. Tiara could certainly take it and more. But no, today she felt like being a tease. She pushed herself deeper and deeper, a fraction of an inch more burying itself in Tiara's inviting depths with every thrust. It was agonizing, the pace carefully calculated to keep Tiara just on the edge of orgasm for as long as fucking possible. Silver wanted to enjoy this.

“Fuuuuuucking hell, Silver, you know I fucking haaate it when you drag this shit oooooout,” Tiara moaned as best as she was capable of. She weakly pressed her hips back against Silver's thrusting, only for Silver to calmly shove her back down.

“Nope. We're going at my pace, lil' miss incapable-of-not-topping.”

“Fuck you, Silver,” Tiara grunted. She weakly pushed herself up, using what little strength she could muster to at least remove her face from the floor. “When this is done I'm gonna kick your a-mph!”

Tiara's train of thought was derailed, and her threat to Silver interrupted, by something big and hard and decidedly cock-like shoving itself down her throat. All twenty five inches, down to the hilt.

“I thought you weren't enjoying yourself.”

“Mmmf. Consider it payback,” Dinky muttered. “She rapes me, I rape her back.”

“I don't think this really counts as rape. She looks like she's enjoying herself at least.”

“Yeah, well, I'm not really in the mood to wait.” Dinky's body quivered, pushing itself firmly against Tiara's face in a vain attempt to bury just a little bit more penis in her tight throat. “Mnnn, I guess your magic piercings work on all your holes. Or maybe you're just really good at suppressing your gag reflex, I don't know.”

“Wanna see how long she can hold her breath? 'cause she can hold her breath for a while.”

“Nah, think I'll just go until I cum and then Twist can take over. I'm trying to avoid getting too much bigger, after all.” Dinky began to thrust, much more wildly than Silver. She pulled herself almost all the way out before plunging right back in to the hilt, again and again and again, faster and faster. Tiara made delightful gurgling noises with each thrust, and the sensation of her fat balls smacking against Tiara's face was surprisingly good.

And getting fatter. She could feel them getting heavier already as each thrust brought her closer to release. “Hey, Tiara, mngg, better hurry up 'n cum before I get an even bigger lead on you~” she said as teasingly as she was capable of.

“Well,” Silver said. “If we're not gonna bother pacing ourselves, I guess I might as well go all out!” She thrust the rest of the way in, before vastly picking up the pace. She fucked Tiara's needy cunt even harder than Dinky was fucking her face. “Hey, Dinky, I think I can feel your cock bumpin' against mine through her womb.”

“Mmmfuck, we do have more'n four feet of cock between us.” Really, they shouldn't have been able to fit all of their cocks into her at all, let alone felt each other through Tiara's organs. But, well, magic. Dinky didn't pretend to understand the logistics behind whatever enchantments Tiara and Silver had on their piercings, and she wasn't exactly in a state of mind to question them. She was just barely managing to cling on to her train of thought through the sensation of giving in to her body's urges.

Which, she realized with a sinking feeling, she probably shouldn't have done. She'd let herself get caught up in the moment and now she had probably passed the point of no return. She could, she supposed, pull out and go back to her original plan of relaxing in the hot tub. Except that the hot tub was thoroughly contaminated with their earlier escapades and it would be very difficult for her to ignore Tiara and Silver and Twist at this point. And besides that, she knew just enough about male anatomy to know that stopping now, while she was so close, would likely just make the inevitable next orgasm worse.

No, at this point, cumming – and the growth that would result – was an unfortunate obligation. She was going to slip up at some point anyway, and it was better to do so now and at least contribute a little bit to Tiara's attempts to better understand their condition that were pretty clearly just an excuse for a small orgy. Dinky wasn't entirely sure if it counted as an orgy with just four ponies, but whatever, she'd already spent too much time thinking about this and all it was really doing was mildly delaying the inevitable catastrophic failure of her willpower. She would have plenty of time to spend thinking about whatever she damn well wanted to in the future. Right now, it would serve her best to get it over with as quickly as possible. Focus on the sensation. The tightness of Tiara's throat, the heavy sway of her overfull ballsack, the heat, the moistness. The primal urge driving her to pump this little slut's face full of hot seed.

Hot seed that she felt really should have come by now. Until now, her new addition had been on a hair trigger, cumming at the first excuse it got. It wasn't that it hadn't been long enough since her last load for it to replenish; she could feel tangible evidence that her ammo had more than replenished enough to blow Tiara up like a balloon. Perhaps it was a matter of her mind constantly wandering away from the sex, but something told her that was a symptom rather than the real cause. Maybe it was waiting for Tiara to cum first, out of some kind of twisted sense of etiquette. Or, she briefly dared to hope, it might just very well be that it had finally reached its limits.

“Oh shit.” Or perhaps it just had a very mean sense of humour. “Oh shit, oh shit, oh shiiiiit~” Her horn sputtered, a thin stream of golden sparks erupting from the tip. The sensation was distressingly familiar. A building pressure at the base of her shaft, slowly but surely compounding upon itself with every thrust. Her body moved on its own, her earlier eager rhythm becoming jerky uneven lurches before fully burying herself balls-deep in Tiara's tight throat. “Oh shit cuminggggggg!”

Her orgasm was slow. She had never thought that orgasms could be slow, not like this. Almost as if her cock knew she was trying to get this over with and was dragging things out, out of whatever spite that a cock was capable of experiencing. She could feel Tiara's throat getting tighter and tighter as the base of her shaft swelled. Bigger and thicker and bigger and thicker as a titanic load pushed its way upward with agonizing slowness. It doubled in girth, and didn't come back down even as the bulge travelled its way upwards towards Tiara's waiting gut. Probably because there was even more cum waiting behind that first shot. It felt like her cock was a firehose that someone had tied a knot in, and even as the water slowly forced its way past the blockage, more and more of a backlog built up behind it.

Silver had came, at some point after her orgasm had started, but Tiara was already showing a noticeable bulge as her cunt was pumped full of thick batter. Tiara came in conjunction with Silver, her cock pumping out far more spunk than would have been expected – had Dinky not experienced the same thing herself, she would have been impressed. With every pulse of semen, it inched bigger and bigger and bigger. Even still, it paled in comparison to Dinky's. It hadn't been that long ago when she'd considered her own fifteen inch meat to be huge, and now Tiara's was past that and she still managed to fucking dwarf it. And she hadn't even grown yet.

Though that fact was short lived. Even as a spent Silver slid out of Tiara, collapsing backwards onto her ass, Dinky's own load finally reached its destination and erupted. An unfathomable volume of cum, fed directly into Tiara's stomach. The bulge of Silver's own load was almost immediately overwhelmed as Tiara's stomach exploded outwards like a balloon. She came, again, Dinky dimly registered. She couldn't tell if Tiara also grew again, what with the large orb of taut flesh in the way, but it was a safe assumption she supposed, which would put Tiara at a respectable twenty five inches. Starting out at ten, five inches per orgasm. They hadn't needed to experiment to find that out, at least – Dinky had figured that much out after her escapades with Twist.

Time seemed to blur together. It felt like days had passed when her orgasm finally died down. As she slid her way out of Tiara's throat and collapsed into an exhausted puddle of flesh on the heated floor, her now thirty inch cock flopped heavily onto her chest. It was, of course, still hard. Why wouldn't it be? “Ooogh.”

“You and me both. Fuck, where were you keeping all of this?!” Tiara rested comfortably on her beanbag chair of a belly, her body sinking in to distended flesh. “Silver, quick, how big am I.”

“Thirty inches, looks like,” a dazed Silver responded. “You prolly came more'n once from that.”

“Ha! Tied for first place, then. And if someone keeps on being a slowpoke with one orgasm to my three, that tie's gonna become a solid lead.”

“I thought we were testing out how this works?”

“Oh, yeah, we are. We're just also making sure that I'm the biggest.” Tiara gave her fat gut a smack, the sound of flesh impacting flesh echoing throughout the pool room. “Speaking of which, though, I'd say we've made good progress on the science front. We know that I'm about as contagious as you, we know that any orgasm with somepony else involved makes us grow, and we know that anal and vaginal are contagious but oral isn't. Next experiment; what happens if I fuck your cunt.”

“Ugh,” Dinky groaned. “I've got a better idea. Let's not and say we did.”

“Oh, come on, you seemed pretty happy to fuck my face just now.”

“Yeah, well, getting fucked is a different matter altogether. Besides, I was already way too big before I got involved in the last round and grew again. Come back when you've come up with a way to make this sucker smaller, then we'll talk.”

“I already said, there's no such thing as too big.” Tiara grinned down at Dinky's prone body. “Only too- hic!” Tiara's belly let out a loud, wet gurgling noise. “Ooooohhhh, this is – hic! – this is newwww~”

“Oh, Celestia, what now,” Dinky muttered to herself even as the wet gurgling intensified. Tiara writhed on top of her gut, moaning in between her hiccups.

Her gut that was getting disconcertingly smaller with every hiccup. “What the fuck?” Silver muttered, more to herself than anything.

“I don't know and I don't fuckin' wanna know,” Dinky replied grumpily. “I am super fucking tired of my penis doing weird shit.”

“There'th a thentence I bet you thought you'd never thay.”

Dinky crawled her way over to the mirrored wall and flopped against it in a rough approximation of sitting. “I'm gonna pass out now. Wake me when this is all done and please try to avoid molesting me in my sleep, okay?”

“I make no promitheth,” Twist replied, earning a sharp, disapproving hiss from Silver that just barely managed to be audible over whatever was happening to Tiara.

“We'll leave you alone, I promise.” That was all Dinky needed to hear. Already she could feel herself slipping into unconsciousness. Darkness danced at the edge of her vision, slowly encroaching its way into the waking world. “I mean, why bother with you when we've got Tiara right here?” was the last thing she heard before slumber claimed her.

“Irresponsible! Dangerously irresponsible!”

Dinky hadn't expected to wake up to shouting. She opened an eye, just a crack.

“Mornin', squirt.”

“Mph. G'morning, Top.”

“I see you had some friends over.”

“You could say that,” Dinky muttered. “I take it mom's not happy?”

“You could say that. Man, I shoulda made popcorn.”

“Thorry, ma'am,” Twist said, apologetically. She shuffled awkwardly, shifting her weight from one leg to the other rhythmically and covering her naked body as best as she could with just her hands. A futile effort, considering how big her breasts alone were. Her cock jutted forward proudly, twenty inches long and drooling and-

“Wait, hold on, is... is Twist's cock fucking candy striped?”

“Looks like it, yep.” It was like a novelty penis-shaped candy cane jutting out of her crotch, white and red entwining along its glistening, twitching length.

“Why am I not surprised?”

“Sorry?! Do you girls have any idea how dangerous this was?”

“I'd just like to say that I was mostly uninvolved, ma'am,” Silver said. She had done a much better job of maintaining her composure than Twist – it probably helped that Derpy was almost a full head shorter. She had also, Dinky noted, grown a second penis. Both members were erect, and both were bigger than she remembered Silver's original cock being. “Like, I am completely throwing Twist and Tiara under the bus here. I didn't lay a single finger on your daughter.”

“Oh, don't fucking lie, you were the first pony here to put your penis in her here.”

“That doesn't count, it was under duress!”

“If I'm getting in trouble for this then by Celestia's ass so are you.”

“You are such a fucking bitch.”

“I don't care who did what!” Derpy shouted, arms flailing wildly. “Look at my daughter! Look at yourselves!”

Tiara grunted sullenly. “'s just sex,” she muttered. She had changed the most of the three. She was taller, if only by a few inches, and her breasts and hips and ass were all significantly bigger. The real star of the show, though, was her penis. It had to be bigger than she was tall by a good foot, and it wasn't even fucking hard. “She's only thirty inches, that's perfectly manageable.”

“She isn't supposed to be any inches!”

“Mom.”

“Didn't you even consider for a second that maybe you shouldn't play around with this until we understand exactly what's going on? You could have gotten hurt or even killed!”

“Mom.”

“Oh!” Derpy immediately stopped her tirade to rush over to Dinky's side. “Are you all right, sweetie?”

“I'm fine, mom. Just... It's fine, okay? No one got hurt and they didn't really do anything wrong other than a little bit of rape at the beginning.”

“A little bit of rape counts as doing something wrong! Very wrong!”

“Please don't shout.”

“Sorry.”

Dinky sighed. “It's fine, mom. I'm not mad and I'm not hurt and they're not hurt so we can just drop the subject for now, okay?”

Derpy's ears flattened against her head. “Well, okay, but I'm still calling their parents.”

“That's fair,” Silver said, shrugging.

“We did kinda rape you a bit,” Tiara added. “Though I mean you did rape me back a bit.”

“Oh that totally didn't count as rape and you know it.”

“Oh, don't you start, miss happily throwing her marefriends under the goddamn bus to get outta getting in trouble. She even said she was raping me!”

“Guys you should prolly stop talking.” Both mares promptly shut the fuck up. “Right.” Dinky laboriously pushed herself upright. “Now, if you'll excuse me, mom's definitely gonna be dragging me to see Dr. Horse again, I could really use a real nap that isn't just me passing out from too much fucking, and I've prolly got a bunch of homework to do.” She shrugged. “Or at least I assume, I've been kinda occupied since Twist brought my notes over, and she didn't leave 'em when she went to get Tiara and Silver, but I figure I've got homework to do, so I'm gonna go do that.”

“Um.”

Dinky stared blankly at Twist. She knew what was going to come next, but still felt the need to ask. “Um?”

“Would you believe that I, uh, kinda forgot your noteth along the way to get Tiara?”

Dinky continued to stare blankly. “Right. Nap it is.”