It shits me when people send me a message in Second Life saying "hi", or "hey", or "are you online?"
Usually I'm offline when I get one of these messages, so when I come online I reply with a "hi". At which point they seem to have no idea who I am or why I am saying hello to them.
Strangely, as I was writing this I got an IM from someone, "hi". "OMG FFS IS THIS FOR REAL?" was what i wrote, but then i deleted it and wrote "hi". I saw the chat history above and they had already said "hi" while i was offline, and i had said "hi" back while they were offline. perfect.
Anyway, it was a short conversation as the next line they came out with was "Have you got a money".