A phrase made popular by a pro gamer named FPS Doug on the internet series Pure Pwnage. FPS Doug says "Boom, headshot" everytime he shoots an opponent in the head in Counterstrike Source or any first person shooter type game.
n00b: OH NO, It's FPS DOUG!!!
- FPS Doug shoots n00b in the head -
FPS Doug: BOOM, HEADSHOT! TAKE THAT N00B!!!