When your playing an online video game and someone on your team or the other team is consistantly having a negative Kill/Death Ratio, weather it be a friend, or the noob your pawning, or both. As a result in them always being negative you can call them a Negative Nathan. They also usually think they are the shit at the game they are playing, which is most often the opposite. Term works best if your friends name happens to be Nathan.
Dude stop trying so hard at the game and just play you Negative Nathan