Rainbow Dash sat there on her sofa, minding her own and listening to some tunes on her MP4 Player. A deep sigh escaped her lips slowly as she took out the earbuds in her ears and looked up at the ceiling in complete boredom. Scanning the table in front of her with lazy vision, she would notice the unattended beverage she had left for herself last night, to which was a paper thin, foil-wrapped container of circular mints and a bottle of dark diet soda.

Slowly, Rainbow Dash would reach one of her limbs towards the beverage and treat, figuring her breath felt a little stale anyways, so she could use the refreshing mints and something to wash them down with. Grasping the cylinder of mints, she wasted no time and would hastily tear open the foil wrappings and would quickly down the whole pack of mints, keeping them in her mouth for a while to savor the flavor before swallowing them down whole, breathing out a frosty peppermint exhale.

Then came the bottle of dark soda, diet. She examined the label closely, revealing it to be done sort of diet cola fizzy pop, generic brand. She shrugged and plopped the top off with a fizzy hiss escaping the bottle. Little did the athlete know is that a sudden foam of fizz seemed to flow out of the opening and escape in a purple pigmant, bubbling over, to which she paid no mind.

Thinking nothing more, she would tilt the bottle do her lips and would begin guzzling down the whole bottle at once with loud, audible gulps, one after another as if it was the last bottle of pop in existence. She took a few moments before she drew back the bottle, halfway empty and paused for a few seconds before she would proceed to burp as loud as she could.

Bleeeeuuuurrrrp!

The rainbow haired cyan female chuckled after a few minutes as if she was rather proud of that one. She waited a few moments for her belly to settle before she quickly slugged down the rest with audible gulping sounds, letting out an even louder burp, quite a bit longer.

BLRRRRRRRRAAAAAAAAUUUUUUUUP!

She sighed loudly and leaned back in the sofa with her limbs folded behind her head. Her belly grumbled and made some odd noises to which prompted her to examine her abdomen briefly but she otherwise shrugged and paid little attention to it. A sudden flare of purple cascaded across her midsection, suddenly feeling like her body was being grabbed by some force to which made her jump slightly in a surprised manner. She furrowed her brow and looked around frantically for something that might have grabbed her and saw nothing, fidgeting in this foreign grip, grunting and struggling in protest.

Upon closer inspection of her tummy, it would appear some sort of purple fog suddenly appeared around her, engulfing the entire area in purple fog with loud hissing sounds, similar to compressed air released from a valve. “What the hay?!” Exclaimed Rainbow Dash as she suddenly felt her midsection being rapidly shaken, causing it to make grumbling and groaning sounds.“Wuhuhat’s goiiiing oooohohohohon?!” She tried to protest, unable to properly form sentences due to the rapid movements. Once movement ceased, she quickly stood up and looked around rapidly.

“Alright, who’s the wise guy?!” Said the cyan female, continuing. “What gives?! Show yourself you cowa-uuuuuuuurp!” She tried to shout out before covering her mouth firmly. The purple fog thickened, binding to her belly, which in terms caused it to gurgle louder, somehow.

Soon after, her midsection begun to quickly expand along with a continuous fizzing sound, almost causing her to regurgitate some foam, somehow keeping it down but couldn't speak due to said foam in her throat. Her shirt slowly begun to stretch in order to compensate her body's growth to the point where the fabric on her clothes begun tearing, while her black, skin-tight compression shorts seemed to have room to spare for now, clinging to her ever growing rear tightly making her butt look rather pronounced, her vest would soon not be so lucky. She would hiccup several times and before long, her belly, breasts and behind expanded easily to four times the original size, creaking and squeaking like a bunch of overinflated balloons rubbing together. Her eyes widened as she seemed quite surprised by the events that were occurring and there was very little she could do to stop it.

Rainbow Dash found herself unable to say much of anything, as her mouth filled with fizz and every word she tried to say was replaced with a series of burps. Laughter could be heard from her right, prompting her right ear to swivel towards the sound.

“Mentos! More Mentos, you guys!” Exclaimed what Rainbow Dash could only assume was her pink friend, Pinkie Pie.

Her eyes widened when even more Mentos appeared in front of her and were forcefully pushed into her mouth, only to be chased down by more diet cola which was forcing her to swallow the whole thing in one big gulp. The limbs in question seemed to be orange in color and felt callused and weathered, which could only mean it belonged to her farmer friend, Applejack.

“Let’s shake ‘er up a bit more! C’mon, y’all!” Rainbow Dash could only cough up some more foam as her rounded belly was grasped by said hands and quickly shaken up and down and around, some audible sloshing of fluids fizzing up more inside of her. The cyan athlete whines in protest as her eyes widened more.

Inside her body could be heard some creaking of horror. Before long, the sounds of groaning could be heard, to which her belly, rear, breasts and face cheeks begun to expand twice as fast, easily reaching widths of that of most hot air balloons, spiking from one-hundred inches to a whopping four-hundred inches in the course of moments.

“Gursh! Mmgh! Plsh! Stughff!” Protested the rainbow female, to no avail. Her compression shorts were now rather tightly bound to her butt at this point, straining to contain the entirety of her massive cheeks, hard enough to where her shorts begun tearing, revealing her rainbow striped underwear underneath. Her face was tinting a few shades of red when this happened, completely embarrassed at the fact that she was slowly exposing herself. Her butt cheeks rumbled a bit, but were otherwise slowly expanding bigger and bigger as time went on, along with the rest of her body.

Pling!

The sound of Rainbow’s jacket’s seams starting to tear was slightly concerning as this surely meant the pressure was already becoming quite unpredictable. A light chuckle of amusement could be heard from her bottom right, along with a familiar sounding voice.

“You think she can handle the pressure if she bloats any faster?” Said the familiar purple Egghead known as Twilight Sparkle. Of course, she would know the answer but would leave that up to interpretation. Rainbow Dash whimpered as she felt two sets of hands grabbing her belly and proceeded to shake her vigorously, causing her belly to groan really loudly.

Rainbow Dash groaned as she grew even bigger, this time reaching the likes of six-hundred inches in diameter, causing her clothes to rip apart, starting with her shirt of which effortlessly ripped apart into many shreds on the ground, followed by her jacket that reluctantly tore into several pieces as well, revealing her rainbow-cladded striped bra, of which had a lightning bolt across the massive cups ending with frilly decor on the bra straps. A deeper blush appeared on her face, prompting another little whimper.

The compression pants struggled to hold on as well, her butt rumbling rapidly. However, they, too, would inevitably succumb to the incredible size Rainbow’s rapidly growing body. They soon would rip loudly, tearing apart and sent pieces flying everywhere in a loud flumping noise to reveal her seamless multicolored panties, of which seemed to also struggle against her massive ass, as well. For now, they seemed to cling tightly to each cheek, making her bum look that much more shapely.

Rainbow Dash was beyond humiliated in response to being in her current state. As such, her cheeks tinted a deep shade of blue. Feeling a pair of hands on her butt, she couldn’t help but clench them tightly the best she could.

“Look at yoooouuuu! You’re bigger than the biggest, bounciest, funnest, fizziest party balloon I have ever seen! We didn’t think you could take it, but look at you now!” Exclaimed Pinkie, giving her growing, rumbling rear a hard slap, earning a groan of discomfort.

Applejack spoke again, “Think she’s had enough, girls? ‘Cause I sure think she hasn’t.” Said the western female, to which Twilight replies, “Not yet. First, we must test her maximum capacity limitations, then we will proceed from there. Now, I would like to start off with some simple compression.” She continued, pressing her belly quite firmly.

Rainbow Dash whines as her belly grew slightly larger, earning Twilight a creak from her belly and rear. Some ripping could be heard from above, prompting the three to gaze up. Rainbow’s bra begun ripping, her nipples poking through the fabric. Before long, her breasts blasted the bra apart, revealing her massively puffed up chest mounds to everyone, making her blush harder and harder. It would appear that even her nipples seemed to puff up a little.

“Lookit them there honkers! I never knew ya for having a big rack of melons, Dash!” Said AJ with a grin. Pinkie giggles and tugs at Rainbow’s panties up hard, giving her a really firm wedgie. “Yeah! Good thing some of your undies held up!” She said with a grin, feeling the fabric she had left begin to tighten.

Seeming to have spoken too soon, Pinkie Pie could feel her panties snap, flinging them across the area to finally reveal her big butt to everyone, her body fully nude and still slowly growing, causing some fizz to gurgle out of her mouth, to which she would keep in her mouth. Pinkie snorted, “Oops! My bad!”

“Oh…my…” said a familiar yellow friend, hiding behind her pink bangs. She seemed to have appeared right behind Rainbow Dash's slowly growing bum, unable to fully comprehend what she was seeing. “Fluttershy! Pleased you could join us!” Twilight said as she quickly wrote something down on a clipboard before pressing her belly harder.

Rainbow Dash wailed if she could, but her limbs now resembled that of nubs with feet and hands on them, unable to move much at all. A loud grumble from her insides was heard as her butt wiggled a little, straining as hard as she could. Her butt cheeks rumbled rapidly as the fizz built up at a quick pace, the creaking getting gradually louder. “Oh…my…!” Fluttershy started as her eyes went wide and begun backing up against the wall in fear. Applejack then interjected, “She’s gonna blow! Do somethin’, ya egghead!”

Twilight sweat a little bit and looked around, hearing that groaning getting louder, those cyan globes straining to hold against the pressure that was quickly becoming unstable. "She's reaching critical mass! I'll...think of something!" Twilight exclaimed as she panicked, still looking around frantically for a solution before it was too late. Then she had an idea, remembering she had an unopened bottle of Sarsaparilla lying around.

Without delay, she grasped a lunchbox that was to the side for later and opened it, tossing out the contents. A Peanut Butter and Jelly sandwich and a grape juice box were launched from the box at high speed. Then, a red apple was next, which bounced off and wedged itself between Dash’s breasts, smashing the apple between her tight cleavage. A bit of foam begun to slowly leak from her rear, prompting more panic. “Got it!” She said as she pulled out a brown bottle, uncorked it and quickly drank down the whole bottle, burped loudly and threw the cork to Fluttershy, since she was the closest.

The cork bounced off her hair and landed on the ground, to which Fluttershy quickly picked it up, her limbs shaking. “Plug ‘er up! Quick!” Applejack exclaimed, to which Fluttershy made little worried noises and quickly plunged her hand forward in one swift movement, pressing the cork as firm as she could between her bum cheeks.

Opening her eyes, the yellow, kind female looked up at the monumentally large, slowly growing rear that was Rainbow Dash’s. She reached a rather ridiculous size, that of which was much larger than most parade balloons, boardering building sized. She swallowed a lump and bit her bottom lip in pure shock, shaking like a leaf. “R-Rainbow Dash sure has grown…” she squeaked out quietly.

Pinkie Pie wiped some sweat from her forehead, “Phew! That was a close one!” She said as she rested her weight on her growing, rumbling, tightening blue cheeks.

“Well...crisis averted! Good work, team!” Said Twilight, turning to walk towards Fluttershy, only to trip on the juice box from earlier, “Oop-!” Was all she had time for, before she tripped and fell against Rainbow Dash's unpredictably huge ass, falling face first against the side of her firm cheeks with a loud thud.

BWUOMP!

Silence fell for a few moments before she heard a loud creak from her friend’s backside. Swallowing a lump as she heard something drop to the floor. “Don’t tell me…” she said before slowly looking down. There lied the cork from earlier, still moving from falling out of Rainbow Dash's rear. “Mmff! Mmff!” She tried to protest as the pressure became too much for her, unable to hold back much longer.

“Get away from there!” Twilight shouted to Fluttershy, who was frozen in fear. Her rear wobbled and creaked louder, a slow, pending sound of doom. “Now she’s really gonna blow! Duck ‘n’ cover!” Applejack exclaimed before hitting the ground, Pinkie Pie doing the same, falling on top of Applejack. Twilight panicked and did the same as well, falling on top of Pinkie. Unfortunately, they were all in the blast zone.

Rainbow Dash could hold back no longer, as her cheeks loosened and her body gurgled. It was coming and it was not waiting. “Fluttershy, get down!” They all yelled. Unable to react fast enough, Fluttershy experiences something hard to put into words. It started off with the sound of a barrage of bowling balls rolling down an alleyway, then a loud gurgle as her behind begun releasing some silent, weak fizzles, as if the calm before the storm. Fluttershy sighed in relief as she leaned against her big butt. Big mistake.

Soon, an explosive, massive stream of powerful, fizzy gas begun to powerfully erupt violently out of Rainbow’s rear, her cheeks flapping quick and rapidly with enough force to pin Fluttershy, Applejack, Twilight and Pinkie to the wall, even projecting her forward and pressed her up against another wall, forcing her to release it all against her best friends.

PFFFFFSSSSSSSSHFLRRRRRRRRRBLRBLRBLRFFFFFFFFT!!!!!!!!

A massive geyser of CO2 and natural gas begun to seemingly endlessly rush out of her body, slowly deflating Rainbow but also forced her friends to take the full force of her powerful back-blasts, perhaps as a sort of revenge for the torment they put her through.

PLRBLRBLRBLRBLROOOOOOOOOOOOOOOMPH!!!!

Still, her rear seemed to explode onto her friends to the point where the cheeks on her face deflated, enabling her to talk. “I-I can’t stoooop!” She exclaimed, having no control. They had no choice but to just let it happen until it’s all over. There was barely any smell, if at all. If any smell was apparent, it would be the scent of cola and mints. Every cloud seemed to have a silver lining, except if this was a cloud, it would be rainbow-colored, fizzy-cola themed.

Over the course of two hours of torture, Rainbow Dash would deflate gradually and slowly, still farting and blasting as hard as she physically could right into her best friend’s faces. After some time, her bum felt quite sore from the cheek flapping fury she have been experiencing. Another two hour passed and Rainbow Dash has deflated to a manageable level, now at a good size of sixty inches of partly liquid but mostly gas. The group fell to the ground once she was done blasting them to the wall and panted. Pinkie stood up first shaken and wobbly.

“Gee wiz, Rainbow Dash! That was a bigger blast than one from the biggest party cannon I own! How’d you do it?” She exclaimed, before Twilight stood up. “I, um…didn’t expect a result quite…” She looked around at everything ruined. “Destructive…still! There’s research to be done!” She said as she pushed her glasses up and tied her hair up neatly. Applejack stood up and picked up her Stetson, “Oooooh no! I ain’t goin’ through somethin’ like that again!” She said as she crossed her arms. Twilight rubbed her head, and looked around. “Very well… looks like we can postpone studies until later. Let’s regroup!” She said before walking off. Pinkie Pie followed suit, but Applejack parted ways.

Fluttershy had slowly gotten up a few moments later, and looked at Rainbow Dash partly inflated and laying against a wall. She groaned and looked back, “N-no hard feelings, right?” She said with a chuckle. Fluttershy straightened her hair and simply walked away, too horrified to say much else. Applejack appeared to Dash’s side and sat patted her, “Bet that felt good, huh?” She said with a chuckle before pressing the cork from earlier up Dash’s naked butt, granting a blush and a squeal of surprise. “By the way…good luck gettin' home in the nude.” She said before walking away, before patting her shoulder firmly. “W-wait a sec! Y-you can’t just leave me here like this!” She said, trying to cover up with what shreds of clothes she had left. “Girls?” She stayed, of course no response. “Come on!” She exclaimed. No response. She sighed and frowned. "At least throw me a towel..." She requested, not expecting such, to which she got none. It would be an experience getting home, of which would be another adventure. For now, she would use the shreds of clothing to cover herself and slowly walked out.