I hate when I meet people (that I know) at the grocery store and all they say is: Hey! What are you doing here? It's not like I'm there to see flying pigs, I only need to buy something like everyone else.
I seriously hate when some people add me on Skype and all they do is just talking about their game all the time. Only because I'm interested into a game this doesn't mean that I want to talk about it all the day.