Superman: A game has rules. Your stunts are just random idiocy.
Mxyzptlk: Okay, I'll give you a rule. You make me say, spell or otherwise reveal my name backwards, and I'll split until our dimensions come into alignment again in about, oh, three months, say give or take.
Superman: I can't even say your name forward. How am I supposed to say it backward?
Mxyzptlk: No, dope! You don't have to say it backward. You have to get ME to say it.
Superman: Say what?
Mxyzptlk: Kltpzyxm! Gosh, you're thick! Now, for the last time - ah, nuts. [Disappears.].