When I was about 13 I had a mean teacher who seemed to enjoy humiliating people. One Winters day he got angry at seeing an open window and asked

“Why don’t you open all the windows?”

So I did. I could sense that he was seething and I knew that I would only be able to get away with it it if I pretended to be a total idiot. A couple of boys, scared that the teacher would get mad, tried to stop me, so I pretended that I could not understand them.

The pay off was wonderful: He was never sarcastic to me again.