I found a new one: Teachers who are overly sensitive. Let's compare and contrast, shall we? My Calculus teacher is a cool guy and really, he will only push you academically if you are motivated. He knows that not everyone likes Math, and he's perfectly fine with that. As he says "If I took people not liking Math personally, I would have quit on my first day."
Now my Chemistry teacher looks like she will cry if you say you don't like Chemistry. And she cries when people cheat on her tests because she thinks people are personally attacking her. And she looks pitiful when he she hears kids say "thank god I never have to do Chemistry again.".