John Travolta has turned down a cameo appearance on "Glee" because producers wouldn't give him enough time to rehearse for a "knock 'em dead" song-and-dance number.
The movie star's Grease sweetheart Olivia Newton-John has appeared on the hit show, but Travolta insists he won't be following in her footsteps.
He tells news show Entertainment Tonight, "They've asked but when I do musicals I train for six to nine months… and a show like that is an on-demand thing.
"I really have a criteria or a pride that I would wanna knock ';em dead, and I don't think I'd knock 'em dead in a week."
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