World of Warcraft (or WoW) has developed its own sort of language of abbreviations and terms. It takes a lot of time to get used to them and you will probably feel like a noob if you ask anyone. So I'll list some of these terms for you, along with a few universal abbreviations you might find.
Noob: This is short for "Newbie". If someone calls you a noob, it's not a good thing. People who don't know what they are doing (usually because they're either new to the game or horribly incompetent) are labeled as noobs. You are now one step closer to not being considered a noob.
LOL: In case you don't know what this means, it means Laugh Out Loud. It is pretty universal but if you ask what LOL means, people usually just respond with "LOL!". They might even say ROFL!
ROFL: Rolling on the Floor Laughing. It must be pretty funny to get this.
BRB: Be Right Back
PST: Please Send Tell. This means please whisper someone. This is usually used when advertising.
WTS: Willing to Sell. This is used all the time in the trade channel.
Aggro: Aggro is extremely important in WoW. It is short for aggression level. Aggro determines who an enemy will attack. In a group this is extremely important because some classes like say a warrior can take damage all day and hardly be bothered while some classes like mages can be killed almost instantly by the same enemies. Keeping aggro on the right group members is extremely important in group dynamics.
Tank: This is the character that has all the armor and takes all the damage in a group. It is usually a warrior, but can also be a paladin, druid in bear form, or even a tough hunter pet. No matter what they may say, PRIESTS CAN NOT TANK. Remember that.
Buff: If someone says "Buff Me" they aren't getting fresh. A buff is a spell or technique that raises one of your attributes. For example priests give power word fortitude, druids give mark of the wild, etc.
Owned, Ownd, Pwned, or PZoWND: These are all extrapolations of OWNED. When someone gets owned, that means they got beat down so terribly that it's just plain humiliating.
Every man dies, but few truly live. Live your life to its fullest, every day as if it were your last.