[A multi part story inspired by my own experience. The first part which is story set-up is almost entirely true from my own perspective (Emily represents my perspective). In this telling every character is at the end of high school so 18 or over]
As Chris carried the pommel horse back to the gym cupboard with his friend Alex, he noticed the girls giggling and admiring the strength of the boys. Gym class, which was mandatory, had become co-ed for the first time this grade, and that that had a mixture of excitement and nervousness in the first few weeks as students checked out each other's physiques, whilst being all too aware they were being checked out themselves. Some of the girls also disliked how over-competitive some boys could get.
Emily and Madison smiled to each other as the boys went by. They both had a thing for Chris, and were impressed with how he looked in his cute gym clothes. The school was a traditional one and had a uniform, including uniform gym clothes, so the students all wore matching t shirts with the school crest and gym shorts which came down to a couple of inches above the knees. The girls noted Chris's toned and hairy legs, and some of the other boys in the class were just as developed, including Chris's friend Alex. Emily and Madison were attractive girls themselves, which hadn't escaped Chris's notice.
The coach blew his whistle and the class sat down. "Ok guys," he said, "we've done with gymnastics for a few weeks, next week we'll be starting swim class". Swim classes used to stop after 9th grade so no one had expected this. Most of the girls and some of the boys immediately felt nervous about the prospect of appearing in swimwear in front of the opposite sex. Some of the boys were picturing the girls in swimsuits, and hoping that they didn't enjoy the sight too much when the class came around. Chris had a sinking feeling in his stomach. Though fairly well defined, Chris was quite shy of his body and felt skinny.
"Girls, bring your uniform one-piece costumes, no bikinis. Boys bring your uniform swim shorts", the coach instructed. "Bring a swim hat if you have long hair. Since it's co-ed, girls you can wear shorts and rash guards over their costumes if you want. You won't swim as well so I don't recommend it, but it's up to you". Emily and Madison both felt relieved they could cover themselves up a bit. Chris was also glad the coach was being lenient, and decided he would wear a surf shirt as well. "I'm guessing boys can as well if they want?" he checked.
"Actually, I'm going to say no as you won't swim as well" coach said.
"But you're letting the girls..." began Dylan, another boy who was shy as he was a bit overweight, but coach interrupted
"I'd rather no one did, but I'm giving the girls special permission for modesty reasons. I know what you boys are like and they might feel uncomfortable. Boys you have nothing to worry about. So swim shorts ONLY. Period." Chris's sinking feeling only got worse when he saw Emily and Madison smiling at him as the coach explained the rules. Chris thought it was quite unfair on the boys.
Next week came and everyone filed into the pool. All of the girls wore shorts over their costumes and most wore rash shirts as well, feeling too shy to show their bodies to the guys. The boys were of course wearing considerably less, and lots of them felt awkward and exposed with the girls seeing their bare chests. The girls weren't complaining. The boys had to wear uniform shorts, which only came down to about mid-thigh, and were quite close fitting. Their bodies were on near full display to the girls. The thought had crossed a few boys' minds that if they got boners over the girls, there would be no way of hiding it. Luckily the girls were more covered up, making that less likely.
As the coach led them in warming up on the pool side with jogging in circles, star jumps and stretches, some of the girls were enjoying looking at the guys' bodies. Emily and Madison admired Chris's toned chest, arms and legs, especially his defined pecs and biceps. They noticed he had hairy armpits and a happy trail, as well as a few wisps of hair on his chest, all jet black like the hair on his head. Even though he was somewhat skinny, he did have some muscles, and the girls loved watching - they were a little turned on by the sight of their half-naked crush, who had nowhere to hide.