In the sixth form, in the 1960’s, some friends (all male) and I sneaked into the school swimming pool during a free afternoon. We had checked and it was not due to be used that day. In the absence of swimming costumes we just stripped off and skinny dipped.
We were playing around with a football and had not heard the main door from the changing rooms open. The first we realised was when the PE Mistress shouted at us. To our horror the pool was now full of a group of fellow sixth form girls and their PE teacher. Apparently their hockey lesson had been rained off so the teacher decided to take them swimming. The PE Mistress ordered us out of the water and told us to line up against one wall so we were facing the girls who were all giggling. We had to stay there for the whole lesson and were totally embarrassed.
When the lesson finished the teacher sent the girls to get changed while she got a slipper to punish us. Several whacks later we were dismissed. The final humiliation was that a large group of the girls waiting outside when we left. Girls can make very cruel comments and they certainly did.