The mIRC ...

AFK	Away From Keyboard
ATM	At The Moment
BBIAF	Be Back In A Few
BBL	Be Back Later
BRB	Be Right Back
BTW	By TheWay
C U L8R	S(C)ee Y(U)ou L8(ate)R
C Ya	S(C)ee Y(Ya)ou
EG	Evil Grin
GMTA	Great Minds Think Alike
IMO	In My Opinion
IMHO	In My Humble Opinion
IRL	In Real Life
JK (J/K)	Just Out Kidding
LOL	Laughing Out Loud
LTNS	Long Time No See
NP	No Problem
OIC	OH I S(C)ee
re	REpeat Hi
RL	Real Life
ROFL/ROTFL	Rolling On (The) Floor Laughing
TTFN	TaTa For Now
WB	Welcome Back