From the description:
 
(this story is currently in the process of being revised & expanded into a multipart format, w/ a few add’tl illustrations… but for now, here’s the original, more condensed version for ya)
 
THE PERILS OF BEING POPULAR
 
Never trust a magic wishing oracle.
 
Jamie’s mind had failed to recall this most utterly basic of pulp TV-show axioms. The strange iridescent crystal necklace he’d received anonymously in his dorm-room mailbox had glimmered with such an enticing allure – made all the more irresistible by the presence of a short handwritten note promising the fulfillment of 3 wishes – that he didn’t even stop to think about the whole “monkey’s paw” trope thing.
 
Understandably skeptical, Jamie figured: well, why not give it a shot?
 
After all, what’s the worst that could happen?
 
Jamie, a geeky, reclusive, shy engineering student in his mid-sophomore year, had always had a great deal of trouble making friends or attracting much attention. His classmates’ eyes seemed to roll right past him; his own gaze often remained fixed to the tiles of the floor in front of him, meandering meekly from lecture to lecture, silent, unnoticed, and uncared-for. His homely appearance didn’t much help matters. Earlier that week, having finally worked up the courage to ask out the girl he’d been dreaming about for almost two years, he’d found himself soundly rejected.
 
Therefore, it seemed logical to Jamie that his first request might as well be a wish to become more popular and more attractive – a wish to be noticed more, and valued more highly, by his peers.
 
He didn’t expect it to actually work or anything, of course.
 
Following the note’s instructions, gripping the gemstone tightly in cupped hands, he whispered his wish, gingerly draping the gilded chain to rest about his neck, and waited.
 
Almost instantly, its radiant, mysterious glow faded into the dull, lackluster glint of an ordinary mineral. He felt a deep, twinging shudder creep its way up & down his spine, and a warm, soft, fluid pulse waft throughout his body, from his core outward to his extremities.
 
And then: nothing.
 
Perplexed, Jamie attempted to make a second wish, uncertain if the first one just didn’t take, or if thing was simply a dud. He wished for infinite riches: something like Jeff Bezos plus one. This time, not even a hint of a response from the crystal. And when Jamie carried on with his classes later that day, he really didn’t feel any more popular than usual.
 
The thing was a dud.
 
Or so he thought…
 
The next day when he woke up, Jamie’s chest felt puffy and swollen, his nipples painfully engorged & erect, saturated with blood and incredibly sensitive. Things only got worse from there: over the course of the next week or so, Jamie reeled with terror as his legs seemed to grow proportionally longer even as his stature shrank from 5’10” to 5’2”, his light brown skin brightened to a muted taffy pink hue, and his hair exploded from a gentle dark-brown buzz cut into an unrestrained symphony of frizzy hot pink curlicues and wild, bursting whiplooplashes.
 
When the faint tattoo outline of three colorful balloons began to appear on either side of his hips, at last Jamie began to fully apprehend his fate: he was transforming into some sick, fetishized anthropomorphic variant of Pinkie Pie from MLP:FiM.
 
He hadn’t even been THAT big a fan of the show, back in the day. He had just watched the first couple seasons or so with his buddies for maybe a few months or so, and then moved on. He wasn’t really a “brony” or anything. Sure, his Facebook avatar had been Twilight Sparkle for a maybe like a couple weeks, but he’d quickly deleted any evidence of that soon after in a bout of justifiable shame. And just because he’d made a handful posts on /mlp/ arguing passionately that Pinkie Pie was OBJECTIVELY worst pony – these things did NOT mean he was ever anything like those detestable “bronies.”
 
Right?
 
Jamie did his best to rid himself of the necklace, in hopes that his nightmarish transformation might somehow cease if he could only get far enough away from its accursed influence. He tried throwing it in the ocean, ditching it in the woods, and hurling it off of a bridge into a runoff stream – but every time, he’d awaken the next day to find it fastened once more around his neck, fueling & nourishing his body’s ineluctable changes.
 
It was hopeless.
 
And so his horrific metamorphosis continued. Jamie’s eyes grew huge & round, his irises going from dark brown to a brilliant azure; his ears grew tall and inhuman, jutting upwards like a pair of catlike radar; his nose grew convex & snoutlike, protruding from his face, petite & equine in shape; his waist slimmed down to almost nothing; his tailbone erupted steadily from his rear at a glacial rate before finally blossoming overnight into a huge, billowing, bushy pink tail that bounced & swayed as he walked, banging into things when he turned and knocking over objects from off of tables.
 
It was humiliating.
 
And so it was with mounting despair that Jamie came to realize that his male organ had been all this time shrinking at a steady pace, burrowing deeper into his crotch, turning itself inside-out – until his genitals had finally become totally inverted, complete with cervix, uterus, and ovary glands: Jamie was now utterly female.
 
She was a girl.
 
The final changes proceeded rapidly from there: Jamie’s hormones flared into overdrive, saturating her bloodstream with savage washes of virulent estrogen, widening her hips at an alarming pace; filling out her ass with tight, buoyant fat; retuning her vocal cords into a high-pitched sugary whine; reshaping her shoulders and the small of her back into a slender, delicate feminine arc; and – to Jamie’s lasting horror – flooding her chest with prolactin and other growth hormones, stimulating mammary tissue development to the point of perilous macromastia.
 
Before her ovaries had fully formed, Jamie’s chest had already grown sore & sensitive from a light, prolonged growth spurt that had left him with a pair of petite, modest breast buds, not much bigger than an A cup or so – but once her new hormones kicked in at full force, Jamie’s breasts shot in a matter of days straight up through the alphabet, growing bigger and bigger, sapping her body’s resources to fuel their single-minded expansion.
 
Jamie’s appetite became voracious, shoveling down food like her life depended on it, every ounce over her body’s energy stolen by the fatty lobes of her greedy, flourishing tits. They burned with hot blood, developing and overdeveloping tissue at a rapid rate, swelling larger and larger, forcing Jamie to retreat to her bed in sheer exhaustion, watching helplessly as they grew after every meal: bigger than apples, bigger than cantaloupes, bigger than pineapples, bigger than her head…
 
Whatever was in that necklace, it wanted to make damn sure that Jamie’s breasts were irrevocably, irrefutably, unmissably, unmistakably BIG.
 
When at last the growth appeared to slow down, Jamie’s new supersized porn-star knockers jutted out from her chest wall like two fat, squishy volleyball-sized teardrops bursting from her torso, hanging down like two huge, overfilled waterballoons, filling up her front, occluding her midsection. Pocked with long stretchmarks at the base from growing so fast, they jiggled like huge bags of gelatin with Jamie’s every breath, upsetting her balance. They felt firm & full & insidiously sensitive – to the point where her entire body twinged with a shuddering spasm of pleasure-pain should her nipples accidentally brush against a dresser table or a doorknob – Jamie’s equilibrium still wasn’t quite used to being nearly a foot shorter, nor was her brain quite used to having to factor in the new, plump, pendulous, melon-sized ballast now swinging from her chest.
 
Worse yet, they seemed to demand Jamie’s constant attention – all too frequently, Jamie’s mental faculties would be seized by some nagging, insistent impulse radiating from the twin cores of her tits, forcing her to drop whatever it was she was thinking about, lie down and knead her greedy tits, inevitably leading to a weak-kneed, shuddering body, a wet pussy, and an hours-long masturbation session.
 
Jamie hated them.
 
When Jamie finally worked up the courage to leave her dorm room – she’d been skipping class for over a week – it was to purchase a bra. Her shoulders, her back, and the base of her hooters had begun to ache from the added strain of her enormous assets.
 
She needed support.
 
Under the cover of night she crept, smuggling her body beneath the comforting shelter of an oversized coat – stuffed with pillows to mask the outline of her absurd, provocative figure. When at last she arrived at the campus store, Jamie nabbed the biggest size bra she could find: a G cup. Rushing to the changing room, before anyone could see, she tried it on.
 
Obscene gobs of titflesh bulged salaciously over and under its overburdened cups, squeezing her overripe bosom in a tight, painful, grip, restricting her bloodflow, bringing tears to her big, Pinkie Pie eyes.
 
It was too WAY small.
 
Defeated, Jamie had no choice but to seek a professional bust measurement from the store’s assistant, who just couldn’t keep her mouth shut about how she had never in her whole life seen such an AMAZING cosplay, nor such a HEALTHY figure. Jamie had little choice but to play along, biting her lip to keep from moaning as the assistant girl’s cold measuring tape slid across the bare surface of her nipples.
 
“52 inches!” she announced. “Gosh, I don’t think I’ve ever SEEN a measurement like that…”
 
Jamie shot the assistant girl a dirty look.
 
“Er… let me see if we have anything for you in the back…”
 
As it turned out, the biggest bra the store kept in stock was a JJ cup – still too small.
 
Jamie was forced to special-order.
 
She needed an M cup.
 
 
Weeks passed…
 
 
Sashaying down the campus commons in broad daylight, the tops of Jamie’s M cup tits wobbled succulently from side to side in their baby-blue tank-top holster, barely restrained by the orthopedic cradle of her heavy-duty brassiere, glinting brilliant & pink in the bright midday sun. Tiny beads of sweat glistened on her taut, stretched skin, slowly dripping down into a deep chasm of luscious cleavage on full display, turning heads, drawing in the gaze of nearly all passerby with their profound gravitational pull.
 
“Hey sugar-princess pony-tits!! Set ‘em free, why dont’cha??”
 
“Yeah, hey, I got 12 bucks, how about a titjob? I’ll bet my 10-inch cock could tickle your little pony snout!! Whaddya say??”
 
Catcallers.
 
Jamie rolled her eyes and flipped them the bird, not missing a beat.
 
“Why don’t you boys go fuck yourselves?” she squeaked in retort.
 
Pinkie Pie’s voice.
 
Flicking her tail indignantly, Jamie strutted in the opposite direction, rolling her hips as confidently as she could muster, pretending she couldn’t hear the inevitable whistles and crude comments about her ass that followed.
 
Once she was out of earshot, Jamie’s posture drooped as she sighed with resignation, feeling every kilogram of the immense twin weights tugging at her ribcage. Once she’d decided to start reattending her engineering classes, things had only become worse for her. Surrounded by hordes of horny, frustrated men, her dignity ached from all the superficial, unwanted attention.
 
And yet…
 
When she got back to her dorm room, Jamie logged in to her OnlyFans account, where her latest stream had managed to accumulate hundreds of dollars (particularly from bronies) in the space of a single day, just by teasing them for an hours or so and shaking her boobs a bit. Since she’d started coming out of her shell, hoards of men at school and online had been showering her with gifts and unwavering adoration, pleading with her to date them.
 
No question about it: Jamie was VERY popular.
 
Jamie looked herself over in her new full-size mirror. There stood the leggy, ludicrously buxom reflection of an outlandishly top-heavy Pinkie Pie, revealingly dressed in a delicious tank-top and booty-hugging short-shorts combo (she just couldn’t help herself; she’d HAD to try them on), clutching her little Gucci handbag (a gift from one of her most avid fans, worth THOUSANDS of dollars – how could she have turned it down??); and there, dangling into the crest of her cleavage, was the crystal necklace that was responsible for this whole mess in the first place.
 
Suddenly, Jamie heard her phone vibrate. She plucked it out of her bag.
 
Unknown number.
 
“Hello?”
 
“Jamie? Is this Jamie?”
 
A male voice. Fratboy-ish.
 
“Hiya!” she stammered, slightly irritated at the sound of her own voice.
 
“Aww shiit, Jamie Pie!! How’ya doin??”
 
Her face went blank.
 
“Ummm… who is this? If you don’t mind me asking?”
 
“You don’t remember? It’s me: Nick!! We met at Jake’s? Last weekend?”
 
Jamie’s blood ran cold. She had gotten totally shitfaced drunk that night – mainly to drown out all the anxiety she had been feeling about her rather uncertain, somewhat existentially-terrifying new situation. Apparently she’d given out her number to some dude she totally didn’t remember.
 
So she faked it.
 
“Ohh yeahh, hiiiya… ‘Nick’… how’s it… how goes?”
 
“You totally don’t remember me, do you?” And he burst out laughing. “Maan, I’m not surprised! You were going fuckin’ CRAZY that night!”
 
Her face flushed hot with embarrassment. Her nipples stiffened.
 
“Wha…”
 
“I shoulda known the spitting image of PINKIE PIE would be a crazy-ass party girl! But, um, hey…”
 
His tone became slightly more serious.
 
“You WERE wearing an IUD or, like, took the pill or something afterwards – right? I mean, we were going at it pretty fuckin’ hard that night… Man, my cock is STILL sore… I must’ve unloaded a couple gallons into that pussy… You SURE you don’t remember??”
 
Jamie’s vagina moistened against her will at the blurry memory of Nick’s dick, even as her conscious mind began to panic.
 
“Uh, anyway, I was thinking… why don’t we get together again tonight for some Netflix or somethin’? I just cleaned up the futon and I got a couple bags of Cheetos and…”
 
But Jamie wasn’t listening. She hung up, dropping the phone to the floor in disbelief with a clatter. And yet – she remembered now. It was all true. She’d drunkenly fucked some random fratboy, raw, bareback.
 
And now – she very well might be pregnant.
 
Jamie flopped her pneumatic frame down on the bed, sitting up, burying her face in her hands, scared out of her mind, furious at that stupid fratboy, furious with herself. Her fat M cup tits bulged on out either side of her torso, still jiggling from the impact of her body hitting the mattress, resting plumply against her lap.
 
“Jamie Pie” had certainly become VERY popular – WAY more popular than the boring, dorky MALE Jamie had been…
 
But at what cost?
 
The dull crystal ornament of her cursed necklace tickled the inner walls of her cleavage. She felt like hurling the thing out the window. But she knew it was useless.
 
Never trust a magic wishing oracle…