Mine was a year 8 boy telling me "Miss! [Headteacher] told us girls should always be allowed to go to the toilet!" when I'd told a girl off for going to the toilet without asking. I asked him why he thought that was, and we established it was because girls have periods. I then asked him to have a look at me (38F) and pointed out that I was quite aware of these issues, having had periods for a very long time myself. "Oh yeah" came the reply 😂