Clean Bathroom Escape

One afternoon, Chris played a prank on three of the schoolyard bullies. They all went after him but Chris was a fast runner and he knew the school grounds like the back of his hand. He thought that he can escape all three of the bullies until he was cornered in the second-floor bathroom. This bathroom also happened to be reserved for the teachers. He has about a very limited amount of time to think of a way to escape the bullies and avoid the possibility of getting caught by a teacher. The punishment, to the horror of the students, is cleaning the bathroom under the supervision of the school custodian. What is a poor trickster like Chris to do?