What is a pet peeve that really annoys you even though it's not that bad?

Being around short tempered people. Every slight or frustration for them is an immature mostly mini but intense explosion. Their family enrages them, their trip to work, their work, their colleagues, their trip home, the super market, the petrol station, things staying the same, things changing ... I avoid them like the plague as friends but A: my son is getting to be one and I have no idea why when myself and my wife just aren't like that B: you can't help but have to work with them sometimes and so on. It's not that I'm intimidated by them - it's that it frays my nerves, it's like at any random point in the day someone could slap a shoe against a wall but there's no rhythm or pattern to it. I can't let go of the idea that they need to fix themselves, like it makes me think "if it pisses you off so much then stop what you are doing/change things for yourself" but realistically I know if you gave them a free pass to change anything they wanted (afore mentioned subjects for example) they'd just move right on to another set of stuff to flip their lid over.