One thing that annoys me is that people ask about other's interests and yet show no interest in communicating! "I play MBD, ADHD, D2 (8 years now), MCI, FTL, GTFO... the list goes on and on!". If these people really wanted to talk about games with other people, they'd realize that not everyone else knows what abbreviations they use in their particular game community.
I mean, it's one thing when we're rambling on at the D2:HU boards - then it's all acronyms but that's inside the group and there's a FAQ handy to get inside the lingo.
Some abbreviations can be safely assumed well-known, such as FPS, (MMO)RPG, PS3 and other generic gaming terms.
(In case someone didn't get the joke: D2 is Diablo 2; HU is the Hell Unleashed mod. I've stopped playing it since I got my Playstation 3. So much fun to be had there!)