Yet another good way to piss someone off.
1) Be wearing headphones.
2) Ask someone a question with a complicated answer.
3) While they answer look at them intently yet blankly.
4) When they stop talking say “Yeah, I still have these headphones on. I didn’t hear any of that. This is really loud.”
5) Ignore any reply and go back to what you were doing.
6) Now someone is angry with you!