People who shorten my name when I've specifically told them my full name.
For example in a meeting, Hello, I'm Bertrude Cabbagio. Hello Bert, I'm blah blah blah.
People who ask what you're doing there when you're somewhere very obvious. Of course I'm going to tell them that I'm running away from a herd of stampeding elephants if someone sees me in the supermarket and asks what I'm doing.
Facebook statuses like 'oh my god, I can't believe that just happened', 57 responses asking what, and the OP saying 'I can't tell you, its top secret MI5 business but it was soooooooo cool'
Oh and definitely people who never talk to you on facebook or in RL, but like pretty much anything you post. Just seems stalker-ish to me. Making sure you know they're watching your every move...
Drivers. All of them, including me. I'm a terrible driver and if someone else drove like me I'd be swearing at them.