"A jockstrap? Well that sucks... nothing else up here." Tom snorted and headed back down the ladder. Jake sighed and followed him. Of course the attic had been a bust. Still, that jockstrap had looked pretty nice... he wondered...
A couple hours later, Tom had left. Jake, curious, had gone back up into the attic and found the jockstrap and taken it back to his room, where he'd set it on the dresser. It was a fairly plain jockstrap, a simple white fabric which looked to be for someone slightly bigger than him. Still... he thought.
Tentatively undressing, he glanced at his meager endowment - a modest 5 inches, around average, but nothing special. Jake wished it could be a little bigger sometimes. Maybe this jockstrap will enhance the appearance, he reasoned. Carefully pulling the garment up, he positioned his cock and balls in the strap to accentuate the bulge as best he could and turned to the mirror.
Jake sighed. Staring back at him was the same Jake he had always known. Scrawny, but not too bad. If he mustered up the energy to work out, maybe he could have some decent muscles. But there wasn't really much to distinguish him. Jake glanced down at the jockstrap. Well at least he didn't look half bad in this...
Suddenly, Jake felt a tingle in his groin. Thinking it was static, he was about to take off the jockstrap when he found that he couldn't. It seemed to be stuck to his skin and wouldn't come off. Then he felt another tingle, and Jake's mouth dropped open as the bulge in the jockstrap began to grow and shift, ballooning outward. The fabric stretched more and more, struggling to contain a growing mass behind it. It actually grew so much that the fabric turned sheer and Jake could see the outline of a huge cock inside the pouch.
Jake felt a final tingle and the growth stopped just as the jockstrap was about to break from the force. Trying again, Jake found that he could now remove it and he did eagerly to see what awaited him...
Out flopped a monster cock, much in excess of Jake's previous size. Tentatively grabbing a ruler in excitement, Jake was amazed to learn his cock reached almost to the end of the ruler soft, at around 11 inches soft if he had to guess. Jake's balls had also grown in size, from ping pong balls to the size of tennis balls. Jake whistled low in appreciation. He didn't know where this jockstrap had come from but it held incredible power.