Here is a small selection of some terms you might hear around the forums, give it a few days and you'll be using them too if you don't already!
AFK - Away From Keyboard
Bump - Bring Up My Post
BRB - Be Right Back
BTW - By The Way
FB - Facebook
FR - Friend Request
F/R - Friend Request
FYI - For Your Information
HTML - Coding used in web pages
IDK - I don't know
IMO - In My Opinion
IMHO - In My Honest Opinion
LMAO - Laughing My Ass Off
LOL - Laugh Out Loud
OMG - Oh My God
PM - Private Message
PMSL - Pissing My Self Laughing
Rep - Reputation
ROFL - Rolling on the Floor Laughing
ROFLMAO - Rolling on the Floor Laughing my Ass Off
TBH - To Be Honest
VM - Visitor Message
WTF - What the F***