The coming-of-age sex comedy 'Youth in Revolt' finds Michael Cera stuck in his same wispy, doe-eyed groove. Even Cera's biggest fans have to admit he has become something of a Johnny One- Note _ that note being high, quavering and perpetually on the verge of fatal mortification. Cera's gift for capturing the adolescent state of chronic embarrassment served him well in the TV series 'Arrested Development.' And it made for perfect casting in such high school comedies as 'Juno' and 'Superbad.' But by 'Nick and Norah's Infinite Playlist' and last year's pseudo-documentary 'Paper Heart,' the falsetto diffidence was wearing thin. In 'Youth in Revolt,' Miguel Arteta's adaptation of the C.D. Payne novel, audiences are still supposed to buy the 21-year-old Cera as high school student Nick Twisp, who lives in sex-obsessed misery with his divorced mother and her succession of loser boyfriends. When Nick meets the disquietingly frank Sheeni Saunders (Portia Doubleday) during a family getaway at a trailer park in California, he decides to do whatever it takes to be with her _ a vow that will entail random acts of theft, arson, dorm-rule violations and cross-dressing. Arteta ('Star Maps,' 'Chuck & Buck') admittedly brings fresh eyes to the story, maximizing its absurdist humor and using animation to stage some of the episodic story's more procedural sequences. And Cera at least tries, with limited success, to break free of his usual mannerisms when he plays Nick's alter ego, a suave sophisticate named Francois Dillinger. But 'Youth in Revolt' strains as it toggles between observational and slapstick humor. What's more, the characters all seem to be speaking in the same arch, hyper-literary drone _ that is, if they're not dumb trailer-park-dwelling rubes. 'Youth in Revolt' is a movie that feels written rather than lived; from 'The Catcher in the Rye' to 'Rushmore,' it's a story we've seen in better versions before. R. Contains sexual content, profanity and drug use. 90 minutes. 