Hard to choose just three, I have so many.

These are not necessarily in order, though.
- Public transport mishaps
A small collection of annoying things other people do, mainly on the bus. First of all, how hard it is to take out the money or bus card in advance, before you step in? Starting to rummage through your bag/purse/pockets when you've gotten on the bus takes unnecessarily lot of time and if the weather is bad, makes other people stand out in cold/rain/whatever for no other reason than you being too lazy.
(The front seats in the buses here are usually reserved for handicaps, elderly people, parents with small children etc.) If you're young and healthy, walk to the back end of the bus. You don't need a front seat meant for someone who can't make it to the back, considering there are usually steps to get there. Again, you're being lazy and inconsiderate.
Getting more drunk than a duck and using public transport. Especially if you're being extremely obnoxious and loud when drunk. It's NOT okay to
jokingly threaten to kill everyone on the bus. Walk home, maybe you'll sober up a bit and realize how stupid you are.
- Constantly pointing out the thing you can't/don't know how to do
Yes, I messed up. No, I don't know how to do it. I got it on the first time you said it, I don't need to keep hearing about it for the next goddamn fifteen minutes. That kind of behavior really makes me want to try again! ...Or not.
Seriously.
- If you borrow my stuff, put it back in the same place where you took it from
Also, if it's a pen from my pencil case, put it back
pointing in the same direction as other pens. They're like that for a reason.
I suppose messing up my things falls into this category, too?