>>105955570The joke is that in order to try and teach elementary school children the difference between 'can' and 'may' (one implying ability and the other implying permission), they will reply "I don't know, CAN you?" when asked if a child can go to the bathroom. However this is infamously obnoxious because not only is it pedantic, but 'can' is perfectly acceptable to use for permission. So the student, annoyed with this, shoots up the school.
