Jamie yawned as he made his way up the stairs, hoping Timmy had run out of energy and fell asleep. He stopped outside the bedroom door, listening in, hoping to hear his Hulk of a brother snoring, but instead heard moans coming from inside. Fearing something was wrong, Jamie burst into the room, expecting his brother to be sprawled on the bed in pain, but found something else entirely.
Sitting on the edge of the bed was Timmy, his giant dick poking out the top of his shorts, his hands rubbing the incredibly erect member as vigorously as he could. He glanced up to see Jamie standing in the doorway in shock, before going back to the task at hand, as if his brother wasn't even there.
"Timmy! What are you doing?!"
"Go...away," he replied, grunting out each word as his masterbating intensified.
"Timmy, you're going to make a huge...mess." Jamie watched as his brother's penis erupted like a geyser, spraying cum over everything. His muscular arms relaxed slightly and he sat back in amazement as the white liquid continued gushing out until finally, miracously, it was over.
When the coast was clear, Jamie stepped into the room, the carpet squishing as he made his way over to his brother.
"Timmy, you can't just do stuff like that."
"Why?" the muscular teen replied, tucking his giant penis back into his shorts before standing up.
Jamie still didn't believe he had to look UP to his younger brother, but he did, only coming up to the bottom of Timmy's nose. Trying to hide his feelings of intimidation, he swallowed hard as he stole a quick glance at Timmy's gargantuan arms and cannonball-sized delts before continuing.
"Because...look at the mess you've made. Do you know how long it'll take to wipe everything off?"
Timmy just shrugged his impossibly wide shoulders, unsure of how to respond, when suddenly he felt something course through his body.
"Whoa," Timmy said.
"What? What is it?" Jamie asked, his sense of brotherly concern overriding his temporary irritability.
"I...I don't know. I feel like..." Jamie stares, dumbfounded, as Timmy starts to inch upward in height, his muscles inflating further, packing even more mass onto his already imposing physique. There wasn't much growth, maybe only three or four inches and 10-15 pounds of muscle, but it was enough for Jamie to feel even more powerless while in his brother's presense.
"Wow! Cool!" Timmy said afterward, his child-like amazement still evident.
Jamie looked up into his brother's eyes, realizing for the first time that he was a full head shorter, his skinny frame and weak body no match for the Herculean mass monster that stood before him. He stared ahead, at a shelf of pectorals that were like thick slabs of marble, at arms that were larger than his head at this point. And he had the power to grow even larger if he wanted...
"I've got to try that again!"
"No. no, no, no!" Jamie says excitedly, nervously grabbing a hand much larger than his own. "Please, Timmy. Just come downstairs with me. Okay? I'll let you watch TV."
Timmy glanced at his alarm clock. "At 12:15 in the morning?"
"Yes, yes. Whatever you want. Just don't play with your penis right now. Okay?"
"Well, okay," Timmy replies, heading for his bedroom door. Even though he's dead tired and in desperate need of sleep, Jamie follows behind, the two of them plopping down on the couch as the TV is turned to a cartoon channel.
Jamie sits with his brother, as he struggles to keep his eyes open, all the while watching to make sure Timmy keeps his hands to himself. As he finally drifts off to sleep, he sees his brother grab his penis, but was too tired to stop him.