I have so many of them. Pretty much all the things people do that make me want to kill the fuck out of them are things they do out of discourtesy or selfishness. So most of them involve driving.
-Being behind me in traffic when I turn right at an intersection or merge onto a highway and then immediately speeding up and overtaking me on the left lane. It's dangerous, you could easily rear end me when I need to go left too, and the only reason you don't is that I fully expect you to drive unsafely.
-Drivers who don't slow down when someone's trying to pull out of a parking lot/driveway into traffic and then honk at them when they pull out. What a fucking surprise, the person signaling pulled out.
-Seeing someone down the road signaling to get into your lane and other drives keep passing by. Why in the fuck would anyone do this? Do they not know that other cars need you to slow down so they can turn? I always slow down to let someone turn into my lane unless I'm already going too fast or am too close to them. I can't get why you wouldn't give someone that courtesy, as if you never need to change lanes.
-Overtaking someone on the road. I won't do it because it's unsafe, because it's rude, and because it's not good for your car to do a lot of sudden accelerating and braking, yet I see it all the time. Someone did it to me today even though visibility was bad because of heavy snow.
-This one happens at intersections where you can turn left at a light and the two left lanes. I'll be in the right one of those lanes and drive to the corresponding second lane on the road I'm turning to when the person on my left nearly hits my driver's side and honks at me. I always don't get why these people think that I don't need to use this lane as much as them since I actually planned my route. I have turned into the lane further out just to avoid getting hit since I could see it coming, and it infuriates me that people have the nerve to try and do this. It hasn't happened nearly as much lately, though.
-Honking at me when I stop to let someone waiting to pull onto a road.
-Honking when I stop at an intersection with a green light because the traffic's backed up in front of me and I don't want to block the intersection.
-Stopping or coming to a near stop in the middle of the road, waiting to change lanes, without putting your signal on. I'll happily blow by these people since they're going to be so rude as to expect me to stop when they won't signal.
-Tailgating a big truck or semi-truck to try and squeeze onto a turn or exit lane. Saw someone jump a median just to do this today. Advertise to the world just how stupid and senseless you are by saving a few seconds on your drive.
-Tailgating when I'm driving over the speed limit. It doesn't matter if you're driving 100 mph; people will tailgate you.
-Arguing with your mechanic over something that doesn't make sense. Admittedly, I've only seen this once, but the guy deserved death for it. I was at Goodyear when the cashier told a guy that they would need to do some kind of work on his engine. The guy got mad and said they should have fixed it last time when he brought in his car...to fix the suspension. The cashier said how that was a different problem. The guy yelled that they should have been smarter and fixed it, like when he brought it to another mechanic and told them about the engine problem. I would have jumped in and said something but since I knew the mechanics there and trusted them, I didn't want to somehow get in a fight that might have gotten me kicked out.
-Pretty much anything, in any way, that involves treating customer service workers badly. Arguing over their policies, blaming things on retail workers that they have no control over, demanding retail workers do favors for you like watch their stuff while they go do something or wait for their order while they first go throw something away then come right back.
One example of this was just stupid. This guy at the bank I worked at wrote down his social security number so I could search for his account. When I found it I threw the piece of paper away in a special bin that all the tellers had that held any kind of sensitive information that was locked away at the end of the day.
The guy asked if it was going to be shredded. I said that it was, but he still wanted it back. Not trusting me (it's just a bank, after all, so it's not like we're fucking used to dealing with sensitive information every day) he asked for it back. I started looking through the bin for it when he thought he'd do me a favor by just looking through it himself.
Now, he just looked dumb. The whole point of this bin is to keep sensitive information in, and he wants to go looking through it because he feels his social security number isn't safe there.
Sure, Mr. Jerk. I'll just hand over all this confidential information to you because you feel this bank doesn't handle your information safely.
I'll stop there. For all of these people, I think that if someone just walked up to them out of nowhere and killed them suddenly, and then walked away, I wouldn't have a problem with it as long as they did it for their discourtesy.