A principal of a small middle school had a problem with a few of the older girls starting to use lipstick. When applying it in the bathroom they would then press their lips to the mirror and leave lip prints.
Before it got out of hand he thought of a way to stop it. He gathered all the girls together that wore lipstick and told them he wanted to meet with them in the ladies room at 2pm. They gathered at 2pm and found the principal and the school custodian waiting for them.
The principal explained that it was becoming a problem for the custodian to clean the mirror every night. He said he felt the ladies did not fully understand just how much of a problem it was and he wanted them to witness just how hard it was to clean.
The custodian then demonstrated. He took a long brush on a handle out of a box. He then dipped the brush in the nearest toilet, moved to the mirror and proceeded to remove the lipstick.
The problem was forever solved.