Poor table manners - I hate people talking with their mouth full or eating with their mouth open. Yuk! And leaning across you to reach the salt or the bread or something and not asking you to excuse them.
Lateness. I have, as far as I can remember, only been late once in my entire life and that was because the bus I was on caught fire. Yes, caught fire.

I don't think there's any excuse for being late unless the transport you are on has a problem. This is a niggle with my other half because he's never on time for anything - he'll be late for his own funeral. If we ever go anywhere and we're expected at, say my parents' around 5pm for a meal, bearing in mind they live 45 minutes away, I have to tell him we need to set off around 3.45pm in order that we're on time because he doesn't think it's important.
And liars. This is the worst one. I've had my fair share of them in my life, including MY PARENTS. My Mum is constantly "don't tell Dad this, don't tell Dad that, don't tell him I bought the present you're giving him because you couldn't get to the shop that sells it, don't tell him, tell him this instead (even though it's not true), blah blah", it's not like he's an ogre, just a bit prehistoric and he has all these rules he tries to make everyone live by although he doesn't himself; and my ex-husband and my ex-boyfriend both quit smoking, supposedly, while I was with them and then continued having sneaky fags for weeks after and told me they hadn't, lying right to my face, assuming I couldn't smell them from 20 feet away. Liars bug the hell out of me, they're just gutless. If they say "yes, I did this, I'm sorry if you're annoyed" I'd be like, "It's ok, don't worry about it," because they owned up. GGRRRR!
