Everything everyone listed but the one that irritates me the most is someone that hits their brakes before they put on their left blinker and I get stuck behind them.
And it boggles my brain how people drive right next to tractor trailers. WTF? I'm only going if I can clear him, otherwise I hang back until it's clear, and then kick it and go. Don't people realize if the guy gets a blow out or any number of other things happen they are toast?