John and Dan came in, talking about the game. John stopped when he saw Billy sitting naked on the couch. He chuckled, "Dude are you jacking off? Go do it in..." John froze, his jaw dropped and his eyes widened as he caught sight of Billy's limp monster.
Dan walked around their older brother to see what was happening. "Is jacking off that thing you told me about?" he asked looking from his big brother John to his naked brother Billy. He finally noticed why John was stunned as he stared at Billy's 10 inch cock hanging over the edge of the couch. "Are they supposed to get that big?" he asked nervously feeling his own thirteen year old prick.
John's gaping mouth twisted into a smile. "My little brother is a MAN. Holy shit that's the biggest dick I've ever seen and your not even boned. How big are you?" he asked proudly.
"uhhh... over a foot hard," Billy guessed. He hadn't seen his new equipment erect yet, although all this attention was getting him there.
"Well, you got me beat," John replied, unzipping his jeans and flopping out his own seven and a half inch cock and healthy bush, completely soft. John was sporting a hefty set of balls also.
"Wow that's a big cock," said Billy, completely underestimating himself.
"Are you kidding? You're a beast! That soft monster's as big my boner," exclaimed John waving his dick up and down with his hips.
"You're both huge. Why does everyone else have a giant dick?" asked Dan, sounding upset. He pulled down his pants to reveal his five inch penis, completely erect and hairless.
"You're just younger than me little man," said John. "And Billy's part horse. You'll get bigger. That's actually a big cock for a thirteen year old."
"Yeah, you're super hung," said Billy, trying to ignore the fact that Dan was as big as he used to be despite being two years younger. "Listen guys, I wasn't jacking off. It's this game. The instructions say play naked, then when I found this magic bottle, THIS happened." He lifted his python and dropped it back to the couch with a thud.
Both Dan and John lit up. "Really?" John was exstatic. The two hurried to strip off their clothes. John lifted his shirt to reveal his muscular quarterback body. His thick arms and heavy pecs bounced and flexed as he pulled his shirt over his broad shoulders. His deep muscle armipits were black with dense hair. His incredible six-pack flexed as he bent down to lower his jeans, exposing his built quads and large calves. Then he removed his size 15 shoes.
Comparitively, Dan's short 5'1" body made him look like a mini-me of John, standing next to his 6'5" brother. He had a lean athletic look, completely shredded and defined with a cut set of abs. He was hairless.
Now nude, the young athlete and the muscle stud stalked over to the couch. Billy couldn't help but notice that now both were sporting boners. As the jocks sat down on either side of him with controllers, Billy couldn't help but feel inadequate, despite his huge manhood.
His brothers both created players and joined the game. The three nude figures set out on a search for the bottles. The first to find one was Dan. It was green and said muscle.
Immediately the video character pumped up. Billy felt squeezed as his younger brother grew wider with fifty pounds of muscle, swelling up to 180, pressing him against his muscular older brother. Dan now definitely looked like John's mini-me. Dan paused his character and hit a double bicep that stunned Billy. John reached around Billy and grabbed a handfull of huge teen bicep.
"Yeah, my buff little brother's a stud," said John, chuckling with pride. He flexed his larger bicep and compared arms, both brothers grinning.
Meanwhile Billy located a new bottle, blue. It said height. The video character grew taller. Billy felt himself strecth as his entire form grew. His body stayed in proportion. Stopping at 6'9" with size seventeen feet and a 12 inch cock, soft. Billy swelled with pride as he was now taller than John.
The game intensified as the brothers searched. Dan found another red bottle, stretching his boner to a full foot with egg-sized balls. The little muscle stud looked like a short bodybuilder/pornstar.
Billy found an orange bottle that coated him with a masculine layer of hair.
The only one who didn't seem to be finding any bottles was John. Billy found this puzzling, since his now shorter big brother was smiling.