People with no sense of humour who drag down a bantering session by refusing to see any irony in what's being said around them. Oh, and people with no sense of humour, who are never sure if what's being said is serious or not. For a lethal example - listen to Richard Whiteley and Carol Vorderman.
Generally the rude, selfish, arrogant and ignorant people who behave as though they are more important than everyone else around them. Everyone can think of specific examples but a few obvious ones are; dropping litter, parking where they shouldn't, pushing in to queues and interrupting.
I DETEST snobbish salespeople or waiters in posh shops/restaurants who make you feel like you don't deserve to be in the place, let alone buy anything. I mean... 'you flippin work here.. you're getting paid to serve me.. don't you dare look down your nose at me you little &*^%$#!'. I know it's silly but sometimes I'm tempted to buy something really extravagant just to prove I can afford it. Arrghh!
People who think they're better than other people and that they have a right to an opinion on the lives of these 'lesser beings' . This really irritates me, I can cope with rude people or mean people, just not arrogant, judgemental ones!
People that use language like the people on Jerry Springer and Ricki Lake. Stuff like "you go girlfriend", "don't go there" etc. I don't want to sound sexist, racist or size-ist (?!) but it's stereotypically fat, black women that talk like this.
people who tell you about their awful experiences with shops or gov.t bodies especially the NHS and when you say did you complain, they say "No I don't like to" I work in the UK NHS ans let me tell you that staff in general are FED UP with pointing out what is going wrong and how to fix it PLEASE if you have had bad service we want you to complain because you will get listened to more than we do....Okay the red flashing in front of my eyes has stopped now, I'm going for a nice lie down