School swimwear
I went to an all boys school. We wore speedos.
Girls in my school who didn't have proper swimwear had to take their knickers off at the poolside cos knickers weren't hygeinic in the pool apparently. They'd be allowed to wear tshirts but we'd be on the pool already and try and get a look as they took their knickers off to see if we could see their vaginas lol! Most of them had long tshirts but some were way too short and you could see everything!