I'm English and went to a mixed secondary school - long enough ago for us all to wear school uniform, which was nice
Very occasionally at school you would see a girl obviously desperately needing a wee, maybe in the classroom or (on a couple of occasions) in the coach on a school trip. Of course I would get rock hard and would be wildly turned on if this happened, but I used to wonder if it was just me or if lots of boys got turned on to a greater or lesser extent when they knew some girl was dying to wee and couldn't go to the toilets.
Once I was on a school trip and was sitting beside a mate on the coach. We became aware that a girl two seats ahead of us and across the aisle (so we had a good view) was needing a wee very badly, and by the time we reached our destination she was absolutely bursting and desperate. I couldn't help noticing that my mate was excited too and had a visible bulge in his trousers, but on other occasions when I saw a girl in that predicament the boys I was with didn't seem excited particularly, and just tended to snigger at the poor girl's plight.
Anyone remember what other boys' reactions were on similar occasions?