Who was the worst teacher you've ever had?

Can’t believe this has never been asked before! At least, it didn’t show up in the list.

At Kansas Newman I was on pace to graduate with a 4.0—until I wound up in the Algebra I classroom. The instructor was, I’m sure, brilliant. Only thing is, he was arrogant and didn’t know how to teach. If a student asked a question for clarification, he’d sigh, and roll his eyes and launch into a long winded “explanation” that made no sense. Needless to say, we quit asking questions. We got the distinct impression that he felt he was trapped in a room full of morons.
Despite that I aced every single homework assignment. Basically, I had to teach the stuff to myself.
The thing that messed everyone up, though, were the tests. He wouldn’t test us over what he had “taught” us so far. He’d test us at the next level, which hadn’t been discussed. We saw things on the test we’d never even heard of.
Well, I wound up with a B- in the class. I gathered homework assignments, which I aced, usually 100%, and my tests, which I usually got a C or D on, and presented them to the school officials.
They were just livid. They had had so many complaints about this instructor, and they were furious that he messed up so many GPAs. They didn’t tell me this, but I figured that was his last year of teaching there.

So, what is your story?