Ok here are some Basic Abbreviations
LOL = laugh out loud
LMAO = laugh my ass off
LMFAO = laugh my fucking ass off
ROFL = rolling on the floor laughing
BTW = by the way
FFS(Slayers personal favorite)= for fucks sake
FYI = for your information
AFK = away from keyboard
N2K = Nice to know
More to come but this is just the basics