The best thing that can be said about this gender-swapped trifle of a riff on Freaky Friday — as a movie in itself — is that it’s entirely inoffensive, even when it shouldn’t be. (The sex ed-class scene, for one, avoids feeling as icky and awkward as it could have.) The best thing we might be saying about this movie 20 years from now is that it was the first time that Zac Efron (High School Musical 3: Senior Year) showed real promise of a career as an adult… that is, if he plays it right and gets lucky and actually ends up with one. As plausibility goes, I’m not sure which is the least likely: that Matthew Perry (The Whole Ten Yards), as a man disappointed with his life, would meet a magic janitor (Brian Doyle-Murray: Daddy Day Camp) who would zap him back to his teen years (while still remaining in the 21st century) so he can “do it all over again”; that a youthenized, removed-from-his-grownup-misery Perry would regress into Efron (Perry, for all his own charms, is no cinema idol); or that the star jock that Perry/Efron was in high school would have been BFFs with the school’s biggest dork (Thomas Lennon [I Love You, Man] as an adult). Still, all that really matters here is not that the script, by Jason Filardi (Bringing Down the House), is easy and obvious, or that Burr Steers’ direction is, thankfully, not dedicated to brutalizing his protagonist the way that it was in his previous flick, 2002’s Igby Goes Down. It’s that Efron dominates the screen with his charm and his effortless comic timing, and makes you long to see what he will do when he gets a chance at an actual grownup role.