Batman gave my my username. Or rather, the Riddler, in Batman Forever. I'm quite certain it has been a common wordplay far before that movie came along, though.
And in case the memory needs jogging...
Bruce Wayne: "We're 5 little items of an everyday sort. You'll find us all in a tennis court". In... A-E-I-O-U. Vowels.
Alfred Pennyworth: Not entirely unclever, sir, but what do a clock, a match, chess pawns, and vowels have in common? What do these riddles mean?
Bruce Wayne: Every riddle has a number in the question and they arrived at this order: 13, 1, 8, and 5.
Alfred Pennyworth: 13, 1, 8, and 5. What do they mean?
Bruce Wayne: Perhaps letters of the alphabet?
Alfred Pennyworth: Of course, 13 is M.
Bruce Wayne: 1 would be A, 8 would be H, and 5 would be E.
Alfred Pennyworth: M-A-H-E.
Bruce Wayne: Perhaps 1 and 8 are 18.
Alfred Pennyworth: 18 is R. M-R-E.
Bruce Wayne: How about Mr. E.?
Alfred Pennyworth: Mystery.
Bruce Wayne: And another name for mystery?
Alfred Pennyworth: Enigma.
Bruce Wayne: Mr. E. Nygma. Edward Nygma. Stickley's suicide was obviously a computer-generated forgery.
Alfred Pennyworth: You really are quite bright, despite what people say.