(VIDEO): Billy Crystal serenaded Jay Leno on his penultimate Tonight Show appearance – a tradition that began when Bette Midler sang for Johnny Carson when he retired from the show. Crystal, who was Leno's first guest 17 years ago, is famous for his musical numbers when he served as the host of the Oscars. His lyrics riffed on everything from Leno's famous chin to his exclusive interview with Hugh Grant after the Divine Brown incident. (Photo: WENN)

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