To list a few;

-Grammar/spelling mistakes
-People walking or driving slowly in front of me and not having room to get around them
-Closed-mindedness
-Ignorance
-Falling asleep at my keyboard (which I just fucking did, again)
-People who think they're somehow better than everyone else
-People who seem to refuse to just read a fucking sign and do what it says
-People who try to talk over others in the middle of a sentence
-People who take a pause, then start talking again the instant you start saying something
-People who don't realize when they've crossed a line and that enough is enough
-Fucking spawnkillers in DayZ

I think I slowly evolved into things that I despise and abhor more than just pet peeves.