Of the game Call of Duty 4:
When playing the gametype "search and destroy", a Ninja Defuse consists of sneaking up behind the member of the attacking team who is planting the bomb at either target A or B and lying in wait behind them for them to finish planting. As soon as they have done so, one begins immediately to defuse the bomb (occasionally actually pulling it from underneath them). The enemy who has just planted the bomb rarely check behind them for a ninja, so concerned are they with watching nearby corners for oncoming enemies. Most effective when all but one member from each team has been eliminated.
Game announcer man: Bomb defused.
Bomb planter:Aw man i just planted! How the hell he defuse that?
Ninja:Aha n00b i just ninja defused you.