People who cut in front you you then slam on their brakes, rather than pulling in behind you.

Or, pople who leave HUUUUUGE space in front of them in a lane of slow moving traffic, rather than keeping anormal space and keeping the traffic flowing steadily.

People who are looking for a house number but don't pull over, just drive at 5mph all down the street!!!

People who don't say thank you when you let them through a gap, and take ages tootling through.

BUT... biggest hate his people who see you ccoming through a gap, and rather than wait, decide they want to get through, then get panic and just stop mid way as they don't want to scratch their car lol!!!