Bigger Mice from Mars

Story by Angrynightmob on SoFurry

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A 30 minute commission for gman420 on FA at https://www.furaffinity.net/user/gman420

Modo, Throttle and Vinnie, of the Biker Mice from Mars cartoon are at the gym, when Vinnie suddenly gets a bigger than expected growth spurt.

Story contains flexing, musk, huge muscles pec play, and a lot of cum from a growing mouse. No one under 18 allowed.

Thanks again for commissioning!


The clangs of metal rang throughout the gym on Mars as a trio of mice were the only clients of the facility at this time. Modo, Throttle, and Vinnie, the trio known as the Biker Mice from Mars, had the place to themselves, and were taking full advantage of the amenities that were on display. Modo was working with a set of free weights, Throttle was on a Butterfly Machine, and Vinnie was on his back, lifting up a massive dumbbell that had over three tons on it. The mice were already rather stacked, but there was always more gains to be had.

They had been working for two hours straight, grunting loudly and soaking their outfits in their sweat and perspiration. Modo and Throttle were just about to call it, getting off of their machine and putting their weights up.

"Yo' Vinnie, let's get outta here!" The grey mouse said, looking over to the white one, still straining under the mass of his bar.

"Allllllmooost!" He huffed out, his arms throbbing as he felt the burn rushing through his body, "I'm soooo clooooose!"

The white mouse was moving the bar gradually up, lifting it up from his straining, huffing chest as his crossed leather ammo belts were soaked clean through with his sweat. Vinnie's teeth were gritting as he willed the bar higher and higher, hefting it up with all the strength that he could manage in his body. He could feel his toes clenching through his boots as he worked it up, inch by inch, up towards his victory.

"That's it, keep it going!" Throttle said, getting behind Vinnie's head and standing above him, "Feel that burn going, then we're going out!"

The grunting and straining from Vinnie grew louder as he clenched his eyes shut, forcing more of the bar upward, before suddenly it felt much lighter in his grip. He gasped out, suddenly shoving the bar completely upward, almost like it was filled with helium now, hefting it triumphantly over the bar.

"That's our boy!" Modo said, giving a few claps about, "Now come on, let's get cleaned up and hit the shower!"

"Hold on..." Vinnie said, balling his hand into a fist a few times, "Right at the end, something seemed off. Like there wasn't any weight in my hands at all. It was almost like..."

His words were cut off as the white mouse suddenly huffed out and hunched over, grabbing at his stomach. The other two mice rushed to his side to help him up, but Vinnie was quickly back to his feet, grunting hard and then suddenly holding his arms to his side. Before their eyes, the finely developed arms on the white mouse were starting to bulk outward. Cords of muscle were expanding and growing on his body, pushing outward as it strained against his fur. Vinnie clenched his arm, flexing it hard and his bicep began pushing upward, further and farther upward. Each flex brought it up another inch as a throbbing vein pushed upward against his skin.

"Holy...!" Modo gasped out, taking a step back as Vinnie continued to grunt and expand.

"Damn bro!" Throttle exclaimed, his eyes wide as he watched Vinnie strain further.

The white mouse was still gasping hard, the growing and flexing of his arms shaking his entire body. He reached down and felt up his chest, and noticed that it was getting tight. His fingers gripped at his straps, and soon saw that they were stuck to his chest, getting tighter on his body as his back and pecs were growing out as well. The white mouse growled outward, feeling his pecs push out and up, brushing against his chin. He tensed up and soon did a crab flex, bringing both of his arms forward and under his chest before flexing his biceps up again, pushing them against his growing front.

Likewise, his back was getting thicker and bulkier as well. His shoulder blades became more defined as his powerful arms required more support. Vinnie's head was getting engulfed in his own pecs and back as he flexed out harder, and for a moment he could only see the growing fuzz and hair of his body as he grew thicker. But soon even his neck muscles began to expand, pushing upward and outward to free his vision.

The massive mouse wasn't done though. His expanding chest was throbbing and the growth was working its way down. His firm abs began pushing outward, bricks forming along his front as his belly expanded. But the slight expansion was nothing compared to his growing pecs, as they jutted further out, doubling in size in the blink of an eye. The sounds of straining leather filled the air before his straps snapped clean off, now exposing his growing nipples that crowned his new chest.

Vinnie's legs and thighs started to thicken as well, and his blue pants and belt couldn't contain the mass that was straining it. Rips appeared in the space-age fabric and a sudden bulking of his thighs ripped them clean off of his body, the tatters drifting down along his feet, which had shredded his boots. All that was left was his belt, and that was dangling off of his growing, black cock.

Modo and Throttle were tenting hard in their own pants as Vinnie was towering over them, having gotten twice as tall as they were and easily four times as thick and muscular. Sweat was glistening and dripping from Vinnie's body as he was still growing right in front of them and there was no sign of stopping. Wet spots were forming on their crotches as the powerful and manly musk of Vinnie was filling the air, mixing with his sweat and permeating the aroma of a pure man in the gym.

"I gotta...get me some of that!" Modo said, rushing up to his growing companion and quickly grabbing the growing dick and stroking it. A powerful flex from Vinnie, straining his muscles even further as they grew outward, was just enough to make Modo gasp out and cum in his own clothing. But the small blast he shot out was a drop in the bucket to the musky pre that was leaking from the cannon in his hands. He had to strip out of his clothes, feeling that massive tool against his naked form.

Throttle was finding himself in the same boat, but draw to the growing, pulsing, and bouncing pecs of Vinnie. He climbed atop the huge nuts of the mouse, moments before a boom echoed out in the gym as they slammed into the ground, and straddled the thick black cock as Modo kept stroking it. Throttle reached upward with both hands, and was just barely able to get both of Vinnie's nipples in his palms as he did so. With all the strength he could manage, he tugged and gripped on the pec crowns, tugging on the fleshy nubs and kneading into it with his fingers.

"Guyssss!" Vinnie gasped out, his voice deep and booming, the bass so thick that the mirrors of the gym started to crack just from the shockwave of it. But he couldn't form more words, only more gasping pleasure as they worked over his massive body. Continuing pulses of strength and power continued to bulge him outward, getting him bigger and bigger by the minute. He could feel Throttle shoving his fingers and thumbs into his nubs, really working over his pecs, before the yellow mouse shoved his face into his crevice. The hair and fur of his body brushed along Throttle's upper body, moving along with his grinding, and making the yellow mouse cum in his pants as well.

He refused to let go of Vinnie's pecs though, and instead started to kick off his pants, and then press even further, grinding his still-hard cock along the path his abs were carving on his belly. With his legs and feet, he also began pressing his toes and feet into the expanding white nuts of Vinnie, feeling the balls churning and gurgling loudly as more hot mouse cum was forming within and stretching them outward.

Modo was doing much of the same. The grey mouse had moved to the head of his cock and was grinding his own arousal along the throbbing slit. Blasts of pre were pumping onto Modo's groin, and his musk was filling even more of the air, even getting Vinnie affected by his own potent scent. He was getting drunk off of his own musk, and began licking at his lips and rubbing over his own body, feeling the hair and fur brush along his fingers and along his arms as he flexed even harder.

After a few more minutes, Vinnie felt his head press against the ceiling of the gym. Upon seeing this, both Throttle and Modo climbed off of the mouse mountain and stood awestruck before his massive body.

"Go! Go! Break it!" Throttle ordered.

Another deep, straining grunt came from Vinnie as the words of encouragement rang through his body. He gathered up all of the strength and power he had felt brewing inside of him and gave one last massive flex.

Each muscle in the white mouse's body, from his calves, to his biceps, to his lats and traps, suddenly bulged outward, expanding with one last explosive show of power. The ceiling began to crack and crumble, tearing apart as Vinnie roared out and broke through the roof of the building, making the spot around where his head had burst through start to collapse to the ground. The roar echoed across the sky, going for miles on the air.

The pure rush and sensation of power made his mighty cock erupt as well, a bulge forming on the underside of his urethra and blasting outward. The pressure and power caught both Modo and Throttle in the blast and they were shot off of their feet and against the back wall of the gym, getting stuck to it, painted and glued onto it by the hot shots of sticky seed.

Vinnie's orgasm lasted thirty solid minutes, flooding the gym with a foot of cum and practically cocooning his companions in his own musky seed. By the time he had finished, Vinnie took a deep, gasing breath, coming down from his growth and orgasmic high.

A wet splash echoed as Modo and Vinnie finally peel off of the wall, painted completely white in Vinnie's cum. They both had blasted as well, adding their own meager contributions to the output.

"Well, that's one way to hit a shower." Modo said.