People who drive in the overtaking lane of Motorways or dual carriageways at about 60 mph and then wonder why I'm getting irate behind them!
Lorries that pull out to overtake other lorries, just as you are about to pass them, and then do one mph faster than the vehicle they're overtaking, meaning you have to sit behind them for the next mile and a half eating their spray at 56 mph!
Highways Agency idiots in 4x4 vehicles who cone off several lanes and cause long tailbacks, when there is no more than a person changing a tyre in the hard shoulder!