Have you ever seen OMGWTFBBQ!!1! and thought someone smashed their keyboard? Ever wondered what those whipper-snappers in that chatroom meant by ROFLCOPTER? Maybe you want to know how to solve the formula "I <3 (.Y.)"?
Sounds like you've been PWN3d by 'net slang. Don't worry, I have the link for you! Those thoughtful, dedicated researchers over at Wikipedia have spent many an hour cataloging and defining all manner of internet slang and compiling it into this impressive list. It covers everything from gamer acronyms to obscure Korean smilies. ^_^
Now you know. And knowing's half the battle. END OF PSA.
Explanation: With my fingers in irc, forums, gaming and various other dark corners of the net, I get a lot more exposure to various 'net slang than certain friends of mine. Finally, there is a link for them. (i.e. Now they can finally decide, with complete certainty, that they really didn't care what was being said in the first place.)
I actually find the fluidity and evolution of 'net slang very intriguing and tend to use a fair (and measured) amount of it in my online communications (for either sarcastic kitsch or real purpose), so the list made for fun browsing material.