21 Jump Street; R, 109 minutes; Carmike Cinema 6

As Jonah Hill and Michael Cera in Superbad reminded us, Hollywood has a long, goofy tradition of hiring post-teenaged actors to portray teenaged characters. Hill and Channing Tatum together in 21 Jump Street suggest a corollary tendency to make age-inappropriateness itself the center of our attention.

An irreverent movie comedy rehash of a premise taken way too seriously by late-1980s TV, it’s also a fun-house mirror for a deranged society in which the less you look like a teenager the more amusing it is to act like one. The question of how we got here has many answers, but one thing to remember about the late 1980s is that it was a time of just enough amiably hysterical anti-drug conservatism to posit the narc as ultimate bad-boy outsider. The premise that baby-faced cops go undercover in high schools, as mounted by a then-fledgling Fox network, somehow launched Johnny Depp’s career.

A hokey but untenable absurdity, in other words, and the new movie can’t resist playing it as such. This 21 Jump Street gets right to work, whisking its duo of rivals-cum-buds right along from high school to police academy to a genteel bike patrol, promptly botched, and then back to school, now preposterously undercover. There, armed with only a bond of mutual incompetence, they uncomfortably discover that recent pieties of political correctness have upended expected social codes. Thus Hill’s chubby sensitive thespian stands tall at last on the precipice of popularity, with Tatum’s blunt beefcake jock consigned to further schooling from a fringe of science geeks.

“Glee” is duly blamed, and the man-boys proceed with their mission particulars. These include negotiations with figures ranging from an angry foul-mouthed boss played by Ice Cube to a smarmy cool-kid drug dealer played by Dave Franco. The drug is synthetic, but its name, HolyF*ckingSh*t, seems wholly organic to users’ experiences.

21 Jump Street offers at least as much personality as should be expected from a film conceived by Hill, scripted by Michael Bacall, also of Project X and Scott Pilgrim vs. the World, and directed by Phil Lord and Chris Miller of Cloudy With a Chance of Meatballs. Actually, the most appealing thing about it may be the sense of slapdash pluralism and conspiratorial abandon of Tatum wanting the world to know he’s actually sweet and fun and funny, and of Hill totally having his back.

These improbable cops don’t tell us much about modern law enforcement, but the film does imply a social contract of sorts. Somehow without falling apart entirely, 21 Jump Street combines flip vulgarity, daffy warmth, and antic wish fulfillment about revisable high-school history. Furthermore, it may be reported, without spoilage, that these filmmakers do their requisite-cameo duty stoutly. In sum, if that show could be said to deserve a movie, this one must be it.