This command kills your player permanently. If in single player (or you are the last person alive on multiplayer), this will end the game. If in multiplayer, you will die and cannot be revived.
The syntax for the killmefast command is as follows:
Find below working examples of the killmefast command.
This is the only way the killmefast command can be used, this command will kill your character and end the game (if not in multiplayer).