Its any oldie but a goodie, Peter Beardsley and Quasimodo
Quasimodo asks Esmeralda, "Am I really the ugliest b**tard in the world?"
"Why don't you go upstairs to the Magic Mirror and ask ?" says Esmeralda.
Quasimodo goes upstairs to the mirror and returns a few minutes later.
As he hobbles in Esmeralda asks "Well, what did the mirror say ?"
To which Quasimodo replies, "Who's Peter Beardsley?"