The philosopher George Santayana famously wrote that ''those who cannot remember the past are condemned to repeat it.'' The philosopher Homer Simpson famously responded ''D'oh!'' The lame high school comedy 17 Again tries charmlessly to synthesize those two schools of thought, preaching a pro forma appreciation of adult responsibilities while making pro forma jokes about campus archetypes including the athlete, the bully, and the nerd. The result is a slack do-over fantasy in which Zac Efron, as a basketball star, looks baffled as to why he hasn't been asked to sing and dance.
Instead, the twinkly, pleasing, 21-year-old pop heartthrob stretches by playing a 17-year-old, twice. At first, Efron's Mike O'Donnell is a class-of-'89 hoops star who forfeits the possibility of a college sports scholarship when he chooses to marry his pregnant girlfriend. (Levi Johnston, consider yourself schooled.) Then, briefly, two decades later, the thicker body of Mike is inhabited by Matthew Perry, playing an embittered dude unable to face his unraveling marriage to that same childhood sweetheart (Knocked Up's Leslie Mann, too enchanting for any man to leave) or to face his own uncommunicative teenagers.
After being splashed with in-the-movies magic water that allows him to experience school life with a Gen-Xer's wisdom, Efron reappears as 17-year-old Mike again, but with thirtysomething gravitas. His kids are now his classmates. And his hot wife is now the mother of those classmates.
In what passes for the most interesting (if cheerfully most irritating) supporting character, Reno 911!'s Thomas Lennon camps it up as Ned, a mega-nerd who has been friends with Mike since back in the day, and who agrees to pose as ''young'' Mike's dad. Still a mega-nerd, Ned is still, not shockingly, a single guy. But now, he's also a technogeek billionaire. 17 Again might have had fun emphasizing how high school geeks inherit the earth. Instead, the filmmakers hang too desperately with the boring popular kids, underestimating the cool dorks. C–