"Cadance! What do you think you're doing?" Twilight shouted. Her voice echoed throughout the caverns beneath Canterlot.
Tossing her hair back, Cadance gave a smirk towards the angry set of ponies before her. "Just having a bit of fun. Being the princess of love means developing a few kinks. I'm sure you and your friends will enjoy it too." The princess' horn glowed and fired off a concentrated beam, hitting Fluttershy and knocking her back with a feeble "meep!"
"Stoppit Cadance! I won't let you hurt my fri-" Twilight's shouting cut out mid-sentence as a beam engulfed her and Applejack. They hovered in the air a moment before falling back to the ground. Pinkie, Rainbow Dash, and Rarity rushed to their side.
""Darling, are you alri-Waaaaaaaah!" The unicorn cried out as she stepped away from Applejack in shock.
"Wut's wrong, sugarcube? Woah nelly!"
Twilight and Applejack's eyes bugged out. Both ponies now had foot long stallionhoods lying flaccid between their legs.
"G-girls... help." Fluttershy cried out.
Everyone except Twilight and Applejack turned and saw a most peculiar sight. Between her legs where there used to be two tiny teats sat fat heaving breasts, with foot long nipples. Each breast was the size of a melon. Just the sight of the ample boobs was enough to make Twilight's cock twitch and harden. In a dazed-like state, Twilight reached between her legs and started stroking her stiff cock, feeling it grow between her hooves. Applejack, her eyes half-lidded in pleasure, did much of the same.
"What the heck is wrong with you two?" Rainbow asked, backing up fearfully.
"That's my faaauulllt," Cadance admitted in a sing-song voice. You see, they have lots and lots of pent up sexual desire just WAITING to burst free."
Rainbow snarled and charged towards Cadance. A pink glow stopped her flight and carefully set her back down. "Don't worry, Rainbow Dash. They will not be harmed, nor is any of this permanent."
"That's hardly the point!" Rarity shouted. "Stop playing with their emoti- huh?"
Rarity's voice stopped mid-sentence as Twilight and Applejack walked over to Fluttershy. The yellow mare, lying on her back looked up at them pitifully.
"P-please... they need filling," she pleaded with her friends, gesturing to the rounded breasts hanging off of her crotch. Each one had grown to about two feet in diameter and now the fat, long, and throbbing nipples at the end oozed a tiny stream of milk from a pin prick of a hole at the end.
With a knowing look, both ponies smiled at Fluttershy and mounted her breasts. Twilight, being very helpful, grabbed one of Fluttershy's nipples and started pushing it onto Applejack's monster of a cock, eliciting a scream from Fluttershy, which soon tapered off into moans. After getting Applejack hooked up, she did the same thing for herself. Pleasure coursed through her body as the nipple hole stretched impossibly wide, acting as a cocksleeve for the student's throbbing meat.
"Girls... I have no idea what I'm looking at," Pinkie Pie said, watching in awe.
Twilight and Applejack started thrusting, their front legs draped over Fluttershy's heaving and wobbling breasts. With each pony pounding their hips against the swelling and sloshing crotchboobs, Fluttershy moaned out, her cries getting higher and higher until they became impassioned cries, escalating with each thrust.
"What do you think Fluttershy meant by "filling?" Rainbow asked.
Rarity stepped back, a nervous look on her face. "I believe we're about to find out..."
If Twilight been concerned before, she showed no sign of it now. Through a lewd smile, she panted and moaned all the while thrusting against the ample tits beneath her. Like a switch, the thrusting became erratic, uncontrolled, and Twilight and Applejack grimaced, pounding the fat crotchtits relentlessly.
"Uh oh. Here comes the icing," Pinkie said, opening an umbrella.
Applejack and Twilight's moans turned into desperate grunts as their cocks started pulsing and twitching. Slamming their hips into Fluttershy's breasts, they cried out as their monster cocks started pumping their payload of cum into the fat crotchtits. Each pulse of cum bloated their shafts as they exploded inside of Fluttershy's tits. The milkfilled bags began growing, filling with the ample cum being forced into them.
Applejack and Twilight felt their rear legs leave the ground as the clung to the bloating tits in their post-coital bliss. Bigger and bigger they grew, from two feet to four feet and even larger as the stream of cum kept pumping.
"That's a lot of icing," Pinkie said with a slack jaw.
Finally, after a minute more of this relentlessly bloating, Applejack and Twilight pulled out of Fluttershy's ballooned tits, falling to the ground. Wearing dumb smiles, they brought themselves close to each other and started into a passionate kiss.
The breasts, bloated with cum, churned and groaned as they kept growing. They visibly pushed outwards by several inches as the nipples, now three feet long and several inches thick dribbled with liquid.
"Your turn," Cadance said, hitting both Pinkie and Rarity with a spell. Both ponies clutched their stomachs and looked up at the swelling breasts enviously.
"Soooo empty! Pinkie said, almost wailing.
"I simply must have something inside me!" Rarity shouted.
Both sex-crazed ponies ran over to the leaking breasts, which continued their steady growth, and hurriedly grasped at the long and hardening nipples, trying push them inside their poorly fitting marehoods.
"Okay. Loyalty or not, I'm out of here," Rainbow said, flaring open her wings. A pink aura held her in place, stopping her escape. "What the... what's going on?"
"You have to attend to some... aftercare, Rainbow Dash," Cadance said in a teasing manner. The pegasus looked around to see what the princess meant until she saw Twilight and Applejack walking over to her, eyes drunken with lust and their cocks rock hard and ready to go once again.
"Uh oh..."
....
Pinkie and Rarity, after much effort, finally forced at least the tip of the giant nipples into their dripping snatches. Gripping the impossibly large nipples, they pulled more and more of the massive nipples inside, stretching their bellies absurdly.
"Rarity! I feel so full!" Pinkie shrieked.
"I know! Doesn't it feel amazing?"
Using her unicorn magic, Rarity grabbed the nipple lodged inside her and started working it in and out like a sex toy pounding her pussy. Pinkie let out a small whine, eyeing Rarity with envy.
"Al-alright, dear. I'll take care if you too,"Rarity said, working the bulging nipple inside Pinkie back forth too.
Both mare's moaned lustfully, unaware of continued churning of Fluttershy's weather balloon sized breasts, or the twitching nipple lodged inside them.
...
Rainbow could do little but watch as Twilight and Applejack approached, their rockhard cocks twitching and bouncing with desire. Spurts and globs of precum oozed from their cocks. Unceremoniously, Twilight rammed her cock into Rainbow's mouth. The poor pegasus' throat bulged as inch after meaty inch worked its way visibly down her throat. Applejack had her eyes on a different prize. Brushing aside Rainbow's tail, she mounted the pegasus' pert and toned flank and thrusted her cock into Rainbow's pussy. Rainbow cried out, muffled by the monster cock spearing her through the mouth, as both ponies sawwed back and forth inside her. She could almost swear their dicks would meet inside her, as long as they were.
...
Rarity and Pinkie shrieked and cried out in pleasured moans as the bloated nipples continued pounding them. Fluttershy was making a bit of noise of her own. With each plunge into her friend's tight marehoods, the pleasure grew stronger and stronger, reaching a plateau.
"Oh Fluttershy! Fill us, darling! We're so painfully empty!" Rarity cried out.
"C'mon, gimme some milk, cause I'm about to cream!" Pinkie shouted.
Despite being attached to two fifteen foot round crotchtits, Fluttershy bucked and kicked as an orgasm washed through her. Each of the wobbling breasts grew outward several inches once more. Suddenly, a burst of milk traveled down and through the enormous nipples impaling the ponies pleasurably.
Both ponies came simultaneously as the huge bulge of milk bloated the nipples, visibly stretching their bellies further. In an instant, their abused canals flooded and filled with the creamy milk. With the giant nipples plugging them up, the liquid had nowhere to go but forward. The dam burst as their tiny wombs filled in an instant, ballooning their belly outward by several feet. Bulge after bulge of milk traveled downward through the nipple, bloating their stomachs out until they touched the ground.
"It's just so much!" Rarity screamed in ecstasy.
Further and further they grew, their bellies rounding out further until all they could do was sit and waggle their hooves uselessly.
"Now I know how waterballoons feel," Pinkie said her tongue lolling out in intense pleasure.
...
"Mmmph! Mmmmmph!"
Rainbow's unintelligible cries fell on deaf ears behind a mouthful of dick. Her entire world consisted of the pain\pleasure of being rammed visciously at both ends. Her eyes rolled up in the back of her head as they continued their pounding.
"Twilight, did you-unf-think Rainbow would make such a-hah-great cocksleeve?" Applejack grunted out between passionate thrusts.
"I'm-oooh-interested to see what her capacity is," Twilight replied, her hooves wrapped around Rainbow's head.
Rainbow, unsurprisingly, had little to contribute to the conversation. She found it hard enough as it was to concentrate through the building orgasm in her stretched pussy.
"Ahhh, oooh, ohhh... Apple-Applejack... I think it's happening again!" Twilight cried out as her thrusting became erratic. Applejack lost rhythm as well, pounding the abused pussy for all she was worth.
Rainbow cried out around the meaty pole impaling her through the mouth as an orgasm shook the pegasus to her very core. A few drops escaped around the edge of her battered pussy as she rode a natural high like she'd never experienced before.
Suddenly, the fleshy tube in her mouth swelled up. Rainbow's eyes fluttered open as she felt the cock in her mouth bulge and pulse. Her pupils became pinpricks as she stared at the bloated nutsack beneath Twilight's legs, churning and bulging with cum. Another painful growth spurt stretched her pussy impossibly wide as Applejack hilted herself inside the pegasus.
"Yeehaw! Get ready for your filling, sugarcube!"
Rainbow's eyes widened in horror as Twilight's cock visibly bulged. Twilight's cock flared inside Rainbow's throat painfully as burst after burst of gloopy cum exploded from her cock, blasting straight into the blue mare's stomach.
"Ohhh Rainbow. Yer gonna get it all!" Applejack screamed as she too blew her load into her spitroasted friend.
In an instant, Rainbow's stomach ballooned, nearly touching the ground on the first blast alone. Once again, the two mares fucking her moaned and their cocks flared as they shot more inside her. Gallons and gallons of cum blimped the poor pegasus, raising her off the ground upon her sloshing and cum filled belly. Soon after, Applejack and Twilight's cocks started pulling out, as Rainbow kept growing.
"Ungh! No... you don't!"
Twilight jumped onto Rainbow's rapidly blimping belly, pushing her cock further down the mare's mouth. Applejack followed suit. Her cock remained buried in Rainbow's liquid tight sealed pussy, letting not a drop of cum to escape.
"Grow for us, Rainbow," Twilight moaned as another burst of cum caused the pegasus' body to explode outward another few inches.
....
Ten minutes later...
"Oh... oh dear."
Twilight surveyed the scene around her in awe and incredulity.
Fluttershy had returned to normal. The only clue that something had been wrong was the puddle of milk lying beneath her leaking marehood.
Pinkie Pie and Rarity lay on the ground with ten foot tall bellies holding them down. Not that they seemed to mind. They simply laid on their backs, rubbing their dome like bellies that sloshed with gallons of milk.
Twilight and Applejack had returned to normal. No longer were they stuck with a foot long penis dripping cum everywhere.
Rainbow, however, was another story. Stoy being the operative word. Improbably, no, impossibly, she had been blimped with enough cum to make her reach the height of a two story building. She moaned and groaned as the current of cum swirled inside her, making her slosh and wobble with the slightest movement.
Cadance’s hooves clinked softly against the crystal. “See? it wasn’t that bad, was it?”
Twilight and Applejack turned and stared at Cadance. Rainbow burped, sending a small burst of cum splashing on the ground.
"Okay, maybe it was," Cadance giggled.