A crazy math teacher I had 2 times in college. He wrote sentences on the board and left blanks that we were supposed to fill in. One time the thing we were supposed to fill in was a period. Then he would talk about stuff that had nothing to do with the book.
The worst was early on. We had a quiz with multiple choice. The instructions said select the correct answer. There was a question where it was like A was correct, B was correct, and D said "both A and B." A reasonable human would select D, which is what everyone in class picked. The instructions did not say that you might select multiple options, but he said we should have selected A, B, and D. The fact that he changed the wording of later tests is an admission that he was not clear. I understand he was trying to teach a strict mathematical way of thinking, but he was a dick about it. People would tell other students to rearrange their classes to avoid him. I had him twice because I hate life and I'm stupid.