This is a phrase used in
counter-strike or any type of PvP / FPS / RTS game. It is used to taunt your opponent when you have either landed an amazing head shot,
double kill, or completely owned a bunch of noobs.
Term came to light on the well known tube video 'mad cause im stylin', where a rap battle took place and the guy who used the line got socked
in the face.
Basically, it is used to anger your opponent and declare your dominance.