We had swim class during PE in HS. There were a few classes where a bunch of guys including myself would come back from the showers to get changed and everyone's underwear was gone. Kind of assumed it was a prank but I was also closeted at the time and it ended up being such a turn on. First of all getting to see a bunch of peers and jocks trying to get their bare asses and floppy cocks into their jeans and then imagining all these guys freeballing around school the rest of the day. Plus, no one could really do the towel dance when trying to squeeze into jeans after a shower so even the shyer guys were on full display. Then there was the unfortunate guy who was wearing sweatpants that day and all the guys knew he was freeballing so kept trying to pants him in the halls. I forever thank that underwear their for starting my fetish towards embarrassment nudity.