-By Frank Lovece

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Somehow, in Back to the Future, when Marty McFly's teenage mother in the 1950s was romantically attracted to what was, unbeknownst to her, her own time-traveling son, Lea Thompson, Michael J. Fox and that "Happy Days" era's ostensible innocence made the situation broad and farcical enough that it played as simply comic misunderstanding.
But when Michelle Trachtenberg's character gets hot for the hard-bodied teen (Zac Efron) whom she doesn't know is really her magically reverted dad, it's just creepy—especially when the two are in a bedroom together and she's on all fours, prowling animal-like, thinking he wants to play a sex game. As if that weren't enough, teen dad shares a sexy dance with his new friend's mom—his unknowing, estranged wife (Leslie Mann)—and the cougar quotient with a minor is pretty discomfiting. I suppose if I were a 17-year-old boy watching this, I'd be all, "Yeah! MILF! Woo!" But I'm not.

I give the squirm-inducing and generally unfunny 17 Again credit for at least being a trailblazer. We've had lots of comedies where a parent (or in one case, granddad) switches body with his or her child (or grandson): Vice Versa (1947 and 1988), Freaky Friday (1976 and 2003), Like Father, Like Son (1987) and 18 Again! (1988), which all hearken back to the pseudonymous F. Antsey's original humor novel Vice Versa (1882). We've also had at least two movies, Big (1988) and 13 Going on 30 (2004), where kids magically become adults, either in their present day (the former) or their future (the latter). 17 Again seems to break ground as Big in reverse—a grownup, solo, reverts to teenhood in the present day.

He does this from the doughy form of Mike O'Donnell (Matthew Perry), whom we're to believe was a high-school basketball star poised to get a full ride at Syracuse. Once we accept that, then it's a snap to accept a magical janitor (Brian Doyle-Murray) who makes Mike 17 again (Efron). In another bit of make-believe, the unemployed Mike happens to have a super-rich friend, Ned Gold (Thomas Lennon), who can buy Mike (now "Mark," Ned's hitherto unknown "bastard son from Connecticut") all the cool accoutrements for Hayden High School, including a souped-up sports car.

Mark believes his mission is to help his kids—daughter Maggie (Trachtenberg), who's fallen for a bully (Hunter Parrish of Showtime's "Weeds"), and picked-upon son Alex (Sterling Knight, a relative newcomer who's joined the Disney Channel stable and whose personable comic timing, befuddled quick-wittedness and sheer courage for a fire stunt are all impressive). Ned, meantime, is essentially stalking the miniskirted school principal (Melora Hardin), who finally agrees to a date in exchange for a bribe (laptops for all students—oddly, since in this upscale school the students would certainly already own laptops). This does lead, however, to the movie's highlight—an unexpectedly funny scene at a restaurant.

Problematically, the pivotal choice made by the original, 1989 Mike seems false: Take a full scholarship, or quit school to be with your newly pregnant girlfriend. It's possible to do both, especially with family help—and, really, is it soooo blasphemous that the film can't even utter the suggestion of a very common, perfectly legal medical procedure called an abortion? That seems a lot less creepy than incest jokes and adult women with minors.