In the middle school girls bathroom, the principal had been battling an ongoing problem of the girls putting on their lipstick and then kissing the mirror above the sink, leaving lip marks on the mirror that were a pain for the janitor to clean every day. So she gathered all the girls and took them into the bathroom.
The principal explained how the lipstick didn't come off very easily and had the janitor present to show them how hard it was to clean.
The janitor said "Every day I have to clean this mirror. I want to demonstrate to you how difficult it is for the lipstick to come off. This is how I clean the mirrors...."
He walked over to a toilet stall, went in and submerged his rag in the toilet. He came out and wrung out the towel into one of the sinks. He then went to the mirror and applied a lot of elbow grease to cleaning the mirrow. Demonstrating how difficult it was to clean...the girls began to wrinkle their faces and some actually turned a shade of green.