public(MIND)

I just stumbles over a short list of the most common shorthands ..

LOL = Laughing Out Loud
ROFL = Rolling on [the] Floor Laughing
ROTF = Rolling On The Floor [Laughing]
AFK = Away From Keyboard
BAK = Back At Keyboard
BRB = Be Right Back
TTFN = Ta-Ta For Now!
WB = Welcome Back
GMTA = Great Minds Think Alike
BTW = By The Way
IMHO = In My Humble Opinion
WTG = Way To Go!