Telefragging

Telefragging is an unknown factor that occurs during multiplayer gameplay in Halo: Combat Evolved and Halo 2. It is a rare occurrence, and usually must be performed deliberately.

Halo: Combat Evolved
In Halo: Combat Evolved, a player must go through any teleporter and remain standing still at the exit of the teleporter. If another player tries to go through the same teleporter, they will not be able to go through. However, the first player's screen will start to go white and their controller will start to shake. Their body will then start to go sprawling away from the teleporter, and it will say that Player 2 "telefragged" Player 1.

Halo 2
In Halo 2, by parking any vehicle in a teleporter you can block it. When another player attempts to use the teleporter, they will not be able to teleport and will die, similar to the effect in Halo: Combat Evolved. Telefragging can be done if you did not update your game for any extra maps.

Halo 3
In Halo 3, you cannot get telefragged. If something or someone is blocking the other end of the teleporter, it will simply state that the teleporter is blocked, and no one will die as a result of this.