Telefrag

From TF2 Wiki

A telefrag is a type of death that occurs to a player while standing on an enemy's teleporter exit as an enemy player uses the teleporter entrance. The player standing on the exit dies and the teleport completes successfully. Telefrags are indicated by a skull and crossbones icon in the recent kills section of the HUD and may include the words "finished off" (e.g "Foo finished off Bar"). They happen very infrequently.

A telefrag is worth no points to any player and adds one to the victim's death count.

Where a telefrag would have normally killed on an ubercharged enemy, that enemy remains alive and invulnerable, but becomes stuck in the player who teleported.