Telefrag

A telefrag is a special kind of frag or kill that results when a player or monster stands on the location of a teleporter as another player teleports to that location. The monster or player who was originally standing at that location will instantly die. Telefrags can be strategically used by a Doom player to kill powerful monsters without using any ammo.

Utilizing an intentional telefrag is considered cheating in a UV_pacifist speedrun.