Telefragging

Telefragging is an unknown factor that occurs during multiplayer gameplay in Halo. It is a rare occurrence and usually must be performed on purpose.

In Halo:CE, the first player must go through the teleporter and then remain standing in the exit of the teleporter. When the second person tries to go through the teleporter, they will not be able to get through, but the first player's screen will begin to go white and their controller will slowly begin to shake. Eventually their body will go sprawling away from the teleporter, and it will say player 2 has telefragged player 1.

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:CE. Telefragging can be done if you did not update your game for any extra maps.

It is not known if you can telefrag people in Halo 3. Blocking teleporters with vehicles can be a useful tactic to prevent surprise attacks.