Ok I've got another one, though this one usually comes in the form of a indictment rather than a question.
"Why did you do do [insert random action] when you should have done [insert totally obvious action]?" or "Why didn't you do [insert totally obvious action]?"
I really, seriously hate being asked why I didn't do something in the past. Yes, MOM, I KNOW I should have started on the paper sooner, and I KNOW I should have started preparing for work sooner. Hindsight is 20/20, I don't need you stating the completely obvious to me. Instead of telling me what I should have done in the past [which I totally can't change btw, I'm not a time-traveler... yet] tell me what I need to be doing RIGHT NOW. You know, something that might actually HELP in the current situation.