lol this one might be better. It's a little short, but it's all I could think of.
AX = AdrenalineX
ATM = At the moment/minute
AFK = Away from keyboard
AKA = Also known as
ADMIN = Administrator
BTW = By the way
BS = Bull sh**
BRB = Be right back
CP = Checkpoint
CBA = Can't be assed
CU = See you
C YA = See you
C = SEE
CS = CounterStrike
DM = Doesn't matter/Deathmatch
EA = Each/Electronic Arts
ETC = Etceteria
ET = Extra Terrestrial (however you spell it lol)
ESC = Escape
EU = Europe
EN = England
EG = Example
FTW = For the win/F*** the world
FFS = For f** sake
F2P = Free to play
FX = Effects
FAQ = Facts and questions/Frequently asked questions
G2G/GTG = Gotta Go
GRATZ = Congratulations
GR8 = Great
GG = Good Game
GL = Good Look
GB = Great Britain
GTA = Grand theft auto
HAX = Hacks (Cheats)
HAXOR = Hacker (Cheater)
HP = Health Points
IDK = I don't know
IDC = I don't care
ID = Identification
IRL = In real life
IMO = In my opinion
JKING = Joking
JK = Just kidding
K = Ok/1000
KK = Ok
L8 = Late
L8ER = Later
LOL = Laugh out loud
LMAO = Laugh my ass off
LAG = Bad connection
LAN = Local area network
M = Million
M8 = Mate
MOD = Moderator/Modification
MSG = Message
MP = Multiplayer
MTA = Multi theft auto
NOOB = New person
NB = Not bad
NEWB = Noob
NFS = Need for speed
NP = No problem
NRG = Energy/NRG - 500
NTY = No thank you
NVM = Never mind
OMG = Oh my god
OMFG = Oh my f***ing god
OWNED = Beaten easily
P2P = Pay to play
PWNED = Beaten easily
Plz = Please
PPL = People
PM = Personal message
RC = Remote control
RL = Real life
RP = Roleplay
ROFL = Rolling on floor laughing
STFU = Shut the f*** up
SP = Single player
SAMP = San andreas multiplayer
TBH = To be honest
TEH = The
TELE = Teleport
THX/THNX = Thanks
TT = Time trial
TTFN = Ta ta for now
TY = Thank you
TYVM = Thank you very much
U = You
UR = YOUR/YOU'RE
UMEOYBFH = Upside down monkeys eating out of your best friend's hands
U1 = Update 1
V1 = Version 1
V2 = Version 2
V = Versus
VS = VERSUS
W/O = Without
W/E = Whatever
WP = Wrong person
WTF = What the f***
WB = Welcome back
X = Something on Adrenaline X (E.G /CX is /CustomizeX)
Y = Why
YW = You're welcome
YO = Hello