When given a mysterious can of homebrew energy drink, Seth should have figured that his time at the gym wouldn’t be anywhere near ’normal’. Now he’s got a growing problem on his hands…

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Seth dropped his duffel bag onto the bench with a satisfying thud and began to roll his shoulders. His long day of work was finally behind him, and now he got to relax doing one of the things he loved most: putting his body under incredible amounts of strain and going through inordinate amounts of work to do so. And he was paying for the opportunity!

Working out didn’t sound so glamorous when it was described that way, but the workouts were familiar patterns he could slip into while blasting his favorite video game soundtracks into his ears. His coworkers didn’t see things the way he did, but they never bothered to try it out. And he never bothered to explain it to them.

After changing his clothes, he tossed his bag into his locker before pausing. Pulling it back out, he reached in and removed a blank aluminum can from its depths. Turning it over in his hand.

Most of his coworkers weren’t interested in his favorite activity, but he recently found out that one, in particular, was. They listened so intently when he took a chance to explain things to them, how powerful he felt during and after it all. How good it felt to see progress, to break all his old records.

They didn’t say much in response, but today, they showed up and gave him this blank can. Told him it was a kind of energy drink, and that he should have it right before the next time he worked out. Seth was… suspicious, to say the least. Nothing good ever came from mysteries like this, and they were incredibly vague about what was in the drink itself. …But the can was so professionally done. It wasn’t like this could be poison or drugs or anything. It was just a blank aluminum can, properly sealed and everything.

Seth sighed and, against his better judgment, cracked it open. He brought the can up to his lips and began chugging it down. The green liquid (glimpsed in the brief second before he started drinking) was carbonated and, unfortunately, room temperature. There was a metallic taste to it that was barely covered by an anemic apple-vanilla combo.

After draining the last few drops, he coughed and sputtered, doubling over as his lungs begged for air. Regaining his breath and standing up, he glared at the energy drink and chucked it back into his locker before slamming it shut.

Just what he needed before his workout, something weirdly inane that baffled his taste buds and soured his mouth with an awkward aftertaste. He grabbed his towel and water bottle, taking a swig to cleanse his palette. He started coughing his lungs out again and was too preoccupied in keeping the water out of the wrong pipe to notice how his cock twitched against his underwear.

===

His coughing fit subsided by the time he reached the gym floor. Tons of relatively new exercise machines of all types lined the room with handfuls of people working out at the various locations. He recognized most of them- he waved at a few friends that were taking a break between reps before starting his stretches.

By the time he was ready, he had the day’s workout ready. It was leg day again, but since a group of newer guys were taking up all the squat racks and trying to figure out the motions, he figured he’d tackle the other parts of today’s workout. Let them get through their workout without the pressure.

He kept an eye on the group’s progress as he worked through parts of his workout. The leg extensions and curls went by quickly and without much incident; as he completed his penultimate set, he saw the some of the guys put the weights back and head off to their next exercises. As luck would have it, they’d vacated his favorite rack. He finished his last set, then headed over to claim the equipment before anyone else could take it.

He adjusted the waistband of his shorts then began to set up the weights for a warm up. Nothing too heavy, just enough for get his muscles used to the strain once again. Once the weights were ready, he picked up the barbell, took a few steps back, and started his reps. Things started out fine, the motions flowing from one to the next. A bit of a wobble at the end of the set, but he’d made mistakes with his balance before. He added weight for his next warm up set and continued his squats, only to have to catch himself on his second rep.

‘What gives?’ he wondered, starting to feel a heat from within himself. ‘I’m still doing warm ups- am I tired now?’

He focused his gaze at the mirror to check himself over and almost dropped the barbell half a second later. The mirror was not showing a body he was used to seeing- sure, he rarely looked presentable when he was mid-workout, but there was something more immediately off about his reflection than his reddened face and his sweat-glistened body.

Notably, the fact that his package was a lot larger than it had any right to be.

It looked like he’d crammed two baseballs and a sock or two down in there. The bulge was obscene, pushing against its polyester prison like it demanded freedom. In search of the fabric to cover itself, it had pulled the waistband of his shorts down to the point of exposing some of his pubic hair. Now that Seth had been shaken out of his workout haze, he could feel it now, almost pulsing against his thighs with an unnatural vitality. ‘Was it still trying to grow?’

A stumble reminded him that he had a significant amount of weight on his back and that losing himself in this new reverie would likely end poorly for his body and the gym’s equipment. ’–And my reputation!’ The thought rocketed to the front of his mind. He didn’t fully know what was going on- if this was somehow some sort of of prank, if his mind or eyes were playing tricks on him, if everything in his briefs was somehow growing out of nowhere- but no matter what, something was happening to him and especially his generous bulge that would need a bit of privacy.

He took a few careful steps forward, racking the bar and stepping out from under the weight. The pulse hammering across his body and the heat bleeding off of him made it feel like he was in the middle of his workout. He turned and made his way to the closer set of doors. Best not to draw too much attention, especially in his current state. The closest place he could find some privacy were the bathrooms in changing rooms. Thankfully, the hallway he just stepped into wasn’t used that much. It’d take him longer to get there, but if it meant he’d get there without being seen, it was worth it.

Now that he wasn’t paying attention to the exercise he was doing, he quickly realized how much things felt like they had changed with him. Every step felt like he was trying to throw the heft on his groin around and let the world appreciate how it bounced off his thighs in turn. Though muffled under his footsteps, he could swear he could hear it slap as it hit, left, right, left, right… And fuck, was it just him, or was it getting more sensitive too? He felt the beads of sweat run down his back or abs, but he swore every minute detail of them trickling across his balls and clinging to his dick.

He might not have been so sure about the size, but he definitely could get used to the sensitivity–

Seth forced himself to stop in his tracks. He’d almost completely bypassed the changing room! God, if he’d missed that because he was too enthralled by his thick cock and fat balls… He shouldered the door aside and–

“–Ah!” Both Seth and Will jumped in shock, neither of them expecting to almost run into each other.

“Sorry, Seth!” Will pulled an earbud from his ear. “I really shouldn’t crank these things up until I start my reps, huh? But, uh, tinnitus, you know?”

“Y-Yeah, uh–” Seth’s mind started running at a thousand miles an hour. He had to get out of the way, but stepping back would mean exposing himself and letting Will potentially get a glimpse. His mind stumbled onto a terrible solution that his body immediately went with. “Sorry, I’ll–” He turned sideways and, in his infinite genius, ended up cramming his newly oversized bulge straight into the doorframe.

His mind lit up with pleasure as his boiling nuts pressed up against the comparatively freezing metal.

He strained to keep himself from moaning. “We can just–”

“Squeeze past each other.” Will rolled his eyes but turned and slipped past without complaining further.

Meanwhile, Seth could have crushed almost anything in his hands with how hard he was clenching them. His eyes filled with stars, and he desperately willed himself to hold still. He couldn’t keep his hips from rocking against the wall, trying to milk every last bit of euphoric sensation from that moment. It every last bit of willpower to finally step back once Will passed and duck into the changing room regardless of who might have been in there.

After a few heart-stopping moments checking the space, he breathed a sigh of relief. He was alone here, at least for the time being. Something caught his attention at the edge of his vision. He glanced down and –

…No, that couldn’t be right. His bulge was somehow looking bigger than it’d looked in the hallway. It looked heavier. Weightier. Fatter. More sensitive. His hands inched closer to the front of his waistband, where his growing, throbbing erection was beginning to pull the band away, exposing the base of his dick and the tops of his… Those had to be his balls, right?

Seth hooked his thumbs around the waistband then began pulling his shorts and underwear down, peeling them off his bulge. Inch by inch, his package became exposed to the air- its impossible size was all the more apparent in the sheer curve of his balls, how far it all sat off his body making him struggle to slip his clothes past it… Fuck, he must have slid it down his full old length, and his cock was still going!

He continued and eventually the head of his cock popped free and begin bobbing higher and higher. It had long since passed his navel and was threatening to stretch up to his pecs. His molten balls still sat fat and heavy, overflowing his poor briefs and seemingly demanding more and more space. As he let go and let them meatily slap straight against his thighs, he swore there was a gurgle and an imperceptible throb.

Almost of their own accord, his hands went south and palmed his balls. He began exploring them in an orgasmic haze, testing their weight and heft, sinking into their mass and feeling all the cum slosh around. Pleasure arced across his mind and precum began freely drooling from his slit as he continued rubbing, squeezing, savoring every moment he could–

“Yeah, I’ll be right back,” a voice came through from the other side of the door to the hallway, “forgot my water bottle.”

Seth acted without thinking. He sprinted to the bathroom stalls as fast as his package, bouncing and bobbing around as it slapped against his thighs, would allow and slammed the door behind himself. He leaned back against the door, mind still reeling from the stimulation. Fuck, that ball massage felt so arousing! And his dick! The way it slapped against his pecs was so–

…Against his pecs? A thought pushed its way to the front of his sex-clouded mind. Just a few moments ago, it was only…

Seth waited until the coast was clear, then looked down at his cock. Cautiously, he encircled his girth with his hand, trying to stimulate it as little as possible. The slightest brushes made him flinch and gasp with pleasure, pushing him to just give in and start jacking off with abandon.

He realized two things about his cock as he pulled it against his chest. First, it was significantly girthier than he was used to. Now, he could barely get around its full girth with his middle finger and thumb. Second, it was definitely larger than when it first popped out of his underwear. It stood tall and proud, reaching past his nipples.

He was breathing heavily. His chest was filled with an incredible energy, desperate for him to do something, anything. On its own, his hand began moving up and down his dick, gathering and spreading his precum to lubricate itself. Was he even fighting it at this point? Could he?

He brought his other hand forward, joining the first below it- Seth could barely believe he was double-fisting his cock, his hands both barely circling it and still having the length to move both hands. He slumped back against the door, drowning in pleasure- his rod seemed to pulse with vigor, hammering against his slick grip, thrumming with an unnatural energy, almost as if –

Oh, fuck!

The thought finally connected though his terminally distracted mind- was it that experimental energy drink? Did his coworker make his whole package explode in size? Was this on purpose?

…Why was this turning him on even more?

A moment of sobriety cut his thoughts. That urgent, throbbing need between his hands wasn’t content with its current attention. With each new pulse, his cock push back into his hands, pushing his grip open and forcing his fingers apart. He watched as, with each pump of his arms to cover his length, the inflamed cock head pushed that little bit further. His balls gurgled and churned, expanding over his thighs as they bloated with jizz.

Seth grunted with each throb as they became more and more insistent. His desires pressed on him more and more- it felt like a wellspring of cum was boiling beneath the base of his cock, desperate with every thrust to break free. The building pressure was driving him insane. He needed to cum, his balls were getting too full.

“Please,” he whispered, voice straining, “please, please, please–” His breathing was fast, desperate. His chest ached and he felt lightheaded, but he was so close! He just needed to go a bit further before–

A wave of pleasure slammed into him and would have sent him straight onto his back if he weren’t already pressed into the stall door. His cock seized hard enough to command his hips to buck, and the largest rope of cum Seth had ever seen blasted out of the end of his dick, slapping against the tile and splashing back all over the stall. Quickly blinded by the droplets, he could only count the clench and surge of pleasure from each rope and the wet sounds of his cock adding to the mess of cum on the wall.

Three, six, nine, twelve… had he just gotten to fifteen or eighteen ropes? Whatever the count was, he could feel his body slow down, each pulse of jizz smaller than the last until a residual orgasmic after shock only shook a few droplets loose off his glans. Exhausted, he let himself slide down the door and slump onto the ground like a wet towel. He took a deep breath as he wiped his eyes clean, dreading to see the mess he’d made.

The stall was an absolute wreck. Cum splattered on the side walls but it caked the back wall, where it was slowly sliding down the wall to similarly drown the toilet. Fuck, if he wasn’t still reeling from the hardest orgasm in his life, he would have believed that this mess was made by someone throwing a dozen or so water balloons full of thick cream.

He looked down in disbelief at the culprit who made this mess. It still stood at attention, though it was starting to droop. Its size was still impressive- by eye, it looked to be a full foot in length and almost as thick as the can the energy drink came in. Several veins crossed its surface, though they were slowly sinking back into the shaft. Beneath it all, his balls were almost as impressive as his cock- each one was a bit smaller than a grapefruit, but not by much.

One question floated to the front of his mind: Why was he still so hard?

A wave of arousal swept over Seth, almost plunging him into a subconscious, animalistic fury. His cock achingly throbbed and his balls gave an angry gurgle.

Seth supposed the ride wasn’t over. Damn energy drinks…