Zig Zagged: Bob kills a party every sessions, with peaks of twice a night. When players start complaining loudly, he became a Care Bear GM, never letting anything bad happen to the party. Until the players start complaining again, and so on.
Averted: The Game Master plays the game fairly, making no special effort to kill or save the party.
Enforced: "This will be the last session I'll GM with you guys, and I'm going to have some fun. Brace yourself."
Lampshaded: "I think we could escape the void blasting gods and we can possibly outsmart the psionic demon Smurf, but I know it would be useless. Somehow, the planet will find a way to explode."
"Argh, why do we keep dying?! Where the hell did those ogres come from?! We're only level 2! In the middle of a city!" "Because it was funny."
Invoked: "Suck it GM! You can't kill me here! IN YOUR FACE!!!"
Defied: When the party is going to get an undeserved bashing, a player stares the GM and spells No. The dragon-riding Chthulus titans steer away for no apparent reason.
Discussed: "Tripping rolls every five seconds? Check. A large amount of falling Rocks? Check. Fighting Dragons at Level 3. Check.Okay,it is official,the GM wants us dead."
The players get fed up with getting killed all the time and decide to walk out en masse, leaving the Game Master without a game.
Or, through some sort of magical plot device, the Game Master ends up being zapped into the world of his own campaign and gets to see what a Crapsack World it is first-hand.
Reconstructed: Bob the sadistic DM is ditched by his friends after a couple of sessions. Later, his closest friend Charlie finds out that Bob has some social issue, and killing parties was his anger management. Charlie gets the group back, and after some costructive critics, Bob softens a little. Only Dick refuses to play again with Bob, saying that he "violates" him, and instead start GMing himself, killing characters by the tons.
Back to Killer Game Master... you do have resist killer game master memorized, right? You don't? Tough luck.