At a High School, a number of girls who put on lipstick in the bathroom began pressing their lips on the mirror, leaving dozens of little lip prints. Every night, the maintenance man would remove them all and the next day the girls would put them right back. 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, she asked the custodian to show the girls how much effort was required. Dipping a long-handled brush into the nearest toilet, he began scrubbing lipstick from one of the mirrors. Afterward, the lip prints on the mirror abruptly ceased.