What are they? And it has to be completely harmless and trivial. Things like spitting, snoring etc don't count.
I have two major gripes with people:
1) The kinds of people who can fall asleep within 5 minutes of going to bed. On my travels I've shared many a hostel with groups of people. And whilst I lie awake in bed, for hours, they nod off instantly. INFURIATING!!!
2) People who can read on car/bus etc journeys. It makes me piggin' sick!! Literally, I can't even read a text message on my phone, in a car, without feeling a little queasy!!! BASTARDS!!!!