[A multi part story inspired by my own experience. The first part which is story set-up is basically entirely true from my own perspective (Emily represents my perspective, other characters' thoughts imagined). In this telling every character is at the end of high school so 18 or over]
"Oh my god Emily, you're going to get me in trouble. We so nearly got caught!" Madison exclaimed as she walked back with her friend to the girls' locker room. She had enjoyed the gym cupboard incident but was very stressed by what just happened.
"Come on Maddie, just try to enjoy yourself," Emily tried to persuade her. Emily had never been more turned on in her life. Having Chris trapped and nude and helpless just did something for her like nothing else could. Whilst getting changed for swim class she was wondering whether to turn her attention to someone else as well... she'd have lots of helpless, shirtless guys to choose from in swim class next.
Once Chris got back to the boy's locker room, he went straight to the washroom to jerk off. Not a chance he could survive another swim class with those girls if he didn't. He came just before the other boys arrived, and as a result was able to manage to contain his excitement for the first ten minutes of the next swim class as they warmed up again. After ten minutes, his friend Alex came in late.
"Sorry coach, lost track of time," he said.
"Well, you can join Chris, Emily and Madison in detention next Monday," Coach said, now go get the ball from the cupboard, we're doing water polo this lesson.
"Alex has such a great body doesn't he?" Emily said after sneaking up behind Chris and resting her hand on his bare shoulder. He was more muscular than Chris, with bulging arms, pecs and thighs, and the beginnings of a six pack. No chest hair unlike Chris but some leg hair and a nice, cute treasure trail. And all was on display to the girls, whether he liked it or not. "He's my second favorite" Emily said as she ran her fingers down Chris's exposed chest. He went red and his dick started to stiffen again. Emily and Madison were both as wet as the pool admiring the cute shirtless guys around them, again enjoying that one luxury that comes with being a girl -- anonymous arousal.
They both enjoyed some physical contact with the guys during the water polo game that followed, but much to their disappointment were on the same team as Chris and Alex, so no excuse for tackling them.
Over the weekend Chris couldn't get last week's events out of his mind. The public humiliation of his huge tent, the almost-blowjob in the gym cupboard. He was absolutely terrified by Emily and Madison might try next, but at the same time, a little excited.