The writing on the wall
In one of the many schools I attended (don’t judge, I get bored easily), there was some idiot so bored that all he (maybe she) would do was write silly things on the bathroom walls. Now that may seem fun and entertaining—especially when it is not your name on the wall—but I can assure you it’s not.
Writing inappropriate things on walls about schoolmates may cause them a lot of misery. Net photo.