Director Darren Stein assays the perils of high school for his first feature since “Jawbreaker’’ (1999), offering a brightly colored, sometimes hilarious gay-themed variation on “Easy A,’’ with some “Mean Girls’’ thrown in for good measure.

Like Emma Stone in “Easy A,’’ the unobtrusive, nerdy Tanner (Michael J. Willet of TV’s “United States of Tara,’’ very good) suddenly becomes highly popular. Only in this case, it’s because he’s been accidentally outed as gay by his more flamboyant friend Brent (Paul Iacono) who remains in the closet.

Because Tanner is now the only openly gay student in town, three girls who lead cliques (Andrea Bowen, Sasha Pieterse, Xosha Roquemore) begin competing for his favors as their gay best friend — but they also expect the fashion-adverse Tanner to conform more closely to stereotype.

“G.B.F.,’’ which concludes with a clumsy parody of the prom climax from “Carrie,’’ offers an admirable message of tolerance for teen audiences — too bad it’s been absurdly saddled with an R rating, even though there’s far less innuendo than in “Easy A.’’

The very appealing cast includes Megan Mullally of “Will &Grace,’’ who memorably offers a running commentary while forcing her embarrassed son Brent to watch “Brokeback Mountain’’ with her.