Update (lol) : The other day this teacher made a cell phone call while we were in the middle of an exam essay. I found that to be very inconsiderate.

Also: people who carelessly "smack" you with their grocerie bags/purses/school bags/elbows/notebooks, etc. when they walk past you whether they're on a rush or not. I understand it's not always on purpose, but I don't see people making an efforth to keep it from happening.