Professor gave extra credit for attending talks by visiting speakers if you got the speaker's signature as proof you were there. I attended but couldn't get a signature from the speaker before they left. Saw the professor there, had a chat with them and left. Professor proceeds to deny extra credit "because there was no proof I was there." We literally had a chat at the talk and you don't know if I was there!? Ok.

That same professor had a habit of essentially bullying students singling them out in class and mocking them if they didnt understand the material (that the professor did a poor job of explaining which is why exams were typically in the 40s and 50s on average) and looking at their reviews indicated that theyd been doing this for years, decades even. So their end of semester feedback came in and they were no longer teaching that course.