1. Reckless and sudden maneuvers just to save a fraction of a second, like roaring around to pass then cutting in front just to brake hard and take the very next exit. Depending on how close, airhorn likely.
2. Not using turn signals - extension of #1. If you signal, I might just let you in. If you jump or bully in front with no warning and make me brake hard, you are getting the airhorn.
3. Tailgating. Yes, I see you. No, I cannot magically make this line of traffic go faster. Yes, I will blister your eyeballs with my LED brake lights. No, I won't go 15 mph over on this single lane road just because you think the speed limit doesn't apply to you. Yes, I'm in the left lane because I'm passing a slower vehicle already. No, I won't floor it to pass just because you say so - I'm already passing at a decent clip and will be out of the way in a few seconds.
4. Inversion of #3 - people without the guts or horsepower to complete a pass after committing to pass. Don't just match speed for miles - speed up enough to get clear in a timely manner. Big rigs I sympathize with because speed limiters, but then the truck being passed should drop cruise down a click so it's not a truck going 65.3 mph passing a truck going 65.1 mph.
5. Hit and run. Never happened to me but I'd be fully prepared to chase someone to the ends of the earth for trying to dodge responsibility for wrecking my stuff.
6. Drivers of huge high end vehicles which only seem to serve as an excuse to bully everyone else on the road. Would be interesting to do a survey about perceptions about drivers of larger or smaller cars than one one being driven, and perceptions about cheaper or higher end cars than the one being driven.
7. Traffic slugs caused by a chain reaction of braking for no reason, delaying everybody for minutes when there was never any obstruction and traffic should have just kept flowing as usual.
8. Idiots who still speed in bad weather thinking AWD or 4x4 means they can ignore the laws of the road and laws of the universe.
9. People who honk and insist I pull out or turn when there isn't space for me to do so because there's traffic coming that the impatient person cannot see. I will go when there's space, and not a moment before. Honking won't make me take additional risk.