People that copy games. It just winds me up the fact that they don't think it's wrong. If they admitted it was at least morally wrong it wouldn't wind me up nearly as much, but somehow they try and justify it (and believe themselves it's not wrong :/ )!
I worked with a guy on £500 a day who copied games, marvelled about it, and ripped the mickey out of people that actually bought them for being 'idiots'. Then he harked on about any slight side-effect of piracy measures as if it's not the threat to his piracy that is the problem but the fact users may want to install 'Robowarrior 4' on 8 completely different PCs they own and isn't it terrible they can't ....
Just winds me up unreasonably - perhaps because my favourite hobby PC gaming is dying not least because of him and people like him, and he finds the whole demise particularly funny :/