What funny things have happened to your class teacher or subject teacher?

The head teacher in high school is very strict. Everyone is doing test papers in the classroom. He found a paper plane from the ground, which happened to be folded from the test paper we made. The teacher flew into a rage and asked who did it! In fact, several students near the window saw the paper plane fly in from the window. It is estimated that the children in other classes folded it and filmed it in the classroom. The teacher smiled himself and blushed.