According to a news report, a certain private school in Washington http://www.51education.net来自无忧教育英语笑话
DC was recently faced with a unique problem. A number of 12-year-old girls were beginning to use lipstick and would put it on in the bathroom.

That was fine, but after they put on their lipstick they would
Press their lips to the mirror leaving dozens of little lip prints.
Every night the Maintenance man would remove them and the next day the
Girls would put them back.

Several memos were posted about this, without effect. Finally the principal decided that something had to be done. She called all the girls to the bathroom and met them there with the maintenance man.

She explained that all these lip prints were causing a major problem for the custodian who had to clean the mirrors every night. To demonstrate how difficult it was to clean the mirrors, she asked the maintenance man to show the girls just how hard it
was.

Under careful instructions, the man took out a long-handled
squeegee(n. 橡胶清洁器), solemnly（庄严的，严肃的） dipped it in the nearest toilet bowl, and scrubbed at the mirror.

There was complete silence in the room.

Since then, there have been no lip prints on the mirror.