To receive the assassination medal in Halo 3 by striking an opponent in the back. Occasionally done by jumping over said opponent while they are in hot pursuit and smacking the back of their head (This is usually performed by more skillful player due to the need for precise timing and control).
Halo Player 1: Why are we in theatre mode?
Halo Player 2: I just have to show you this awesome Ninja I pulled on (Insert Pro Gamertag) last night in MLG.
Halo Player 1: Is it anything like the other 6 you have in your Fileshare already?
Halo Player 2: Better..