Accidental and often grossly inappropriate mistyping of a left bracket instead of a right bracket when expressing a feeling of sadness and instead displaying joy.
The opposite can also apply, where instead of the intended joy, you express despair, sadness and woe!
Jane : I'm so upset, first my boyfriend left me, then my house got repossessed, and today my cat got run over by a lawnmower!
John : :)
Alvin : Hey Julie, I just got tickets for a weekend in Venice!
Julie : Really? :(
A corruption of the much more frequently used MPS (Mega Piss Skill) - but instead of relating to urinary annihilation of a office cubicle/train toilet/public bog,is short for Mega Gas Skill.
A coded means of relating to a friend in a crowded place (Lift, Bus, Train , Plain, Automobile ) you've just increased your carbon footprint with a noxious emission.
Global warming begins with the seat of the pants, and violation of the olfactory organ.
Ted : "I've got MGS"
Petey : "I know because my nose is bleeding and my eyes are running."