Mxyzpixilated

Clark Kent: What do you want?

Mr. Mxyzptlk: Laughs! You see, for centuries now, I've been pitting my interdimensional magic against schmoes who thought they could go 15 rounds with the old master! You know the stories about genies, imps leprechauns?

[Mr Mxyzptlk levitates Streaky the cat, which Clark flies up and catches]

Clark Kent: You?

Mr. Mxyzptlk: Yep. After a while, I became bored with your basic rank-and-file human dolts. But then YOU showed up, SUPERMAN!

[Clark turns into Superman with a flash]

Mr. Mxyzptlk: You, my friend, are the ultimate challenge! We're going to have very merry games, you and I!

[starts flying around in circles]

Superman: A game has rules! Your stunts are just random idiocy!

Mr. Mxyzptlk: Okay, I'll give you a rule! If you can make me say, spell or otherwise reveal my name backwards and I'll split, until our dimensions come into alignment again in... oh, three months, give or take.

Superman: I can't even say your name forwards - how am I supposed to say it BACKwards?

Mr. Mxyzptlk: No, dope, *you* don't have to say it, you have to get *me* to say it!

Superman: Say what?

Mr. Mxyzptlk: Kltpzyxm! Gosh, you're thick! Now, for the last time... ah, nuts!

[vanishes]