In an interview on Piers Morgan Tonight, the shock jock calls the NBC late-night host "insane" and accuses him of stealing sketch ideas.
"Jay is a crook and the world knows exactly what he's up to. He steals a tremendous amount of material," The New York Post quoted Stern as saying."This guy's ripped off like 10 major things from my show."
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Stern also adds he's baffled that Leno has beaten fellow late-night host David Letterman in the ratings.
"It's beyond my comprehension," Stern says. "America must be filled with morons who at night lay in bed — the ones who are watching him, they must be in a coma."
Stern's interview airs Tuesday at 9/8c on CNN.