At one school, a group of teenagers painted their lips daily with lipstick, and then kissed the mirror in the bathroom, leaving behind greasy lip prints.
Anyone who has even once cleaned a glass with the remains of something greasy on it, is certainly well aware of how thankless of a job it is. It takes a lot of time, requires the use of strong detergents and generally leads to frustration. Not surprisingly, the school janitor very much disliked doing this and even reported such situations to his supervisor.
Unfortunately, the appeals of the headmistress, who publicly prohibited this practice, did not help. On the contrary – the forbidden fruit tastes best, after all – the girls continued their practice without fear of any consequence.
Then the janitor came up with an idea of how to get the teenagers to unlearn this practice once and for all. And, as it turned out, his idea was was a bull’s eye!