Drivers who hit the accelerator on an amber when they can see a queue of cars in the opposite direction wanting to turn right on the same amber light (who have all queued for longer).
Drivers who live in cities but choose to own unreasonably massive cars and proceed to drive down the middle of two way roads and take up two parking bays every time they go shopping
Drivers who take a thousand years to turn left (where there are no hazards, traffic or any cause to drive under 15 mph)
When drivers don't thank you for letting them through (when you had right of way)
Overly loud sirens - I can hear an ambulance from approximately 2 miles away but can't tell what direction it's coming from or if it will even head towards my road. They're too damn loud.
Overtaking a really wobbly and slow cyclist only for the red lights to betray you and let them overtake you again. Then have to try and safely overtake them again while they work out what the minimum speed for staying upright is.
Cyclists on e-bikes who refuse to pedal when you're waiting for the junction they're passing to clear
Pedestrians who pass in front of your car at a crossing just when the traffic clears
LED laser beams
People who drive for pleasure and just waft around causing nuisance to everyone else