Appealing performers and a couple of very funny moments don’t make up for a lazy and generic script in this predictable farce about two black male FBI agents who go undercover as spoiled rich white girls. I knew we were in trouble when there was a “Hammer Time” joke in the first few minutes, a reference way past its sell-by date. And a Bjork swan-dress joke? In white chick terms, that’s so yesterday.

In rap music terms, this movie samples characters and plots from many other movies, including the already vastly over-used (attractive and principled but do-things-their-own-creative-way law enforcement types always getting chewed out by choleric superiors until one of their wacky schemes pays off and they get to be heroes) and the already done so brilliantly and distinctively that no one should ever try them again (whoever thought of appropriating the “Junior” plot twist from Some Like it Hot should be sent to the screenwriter equivalent of solitary confinement).

Even the movie doesn’t even appear to paying attention to its plot. Movies don’t have to be logical; they don’t even have to make sense. But sloppy inconsistencies like the ones here become a distraction that interferes with the ability of the audience to enjoy even the jokes that work.

Shawn and Marlon Wayans, apparently both the Zeppo Marxes of the talented Wayans family, play FBI agents Kevin and Marcus Copeland. It is typical of this movie’s problems that no one had the energy to give these characters anything resembling a personality. They are almost indistinguishable from each other except that one has a hysterically jealous wife and the other has a goatee and is single.

After they bungle a drug bust, they are assigned to escort the Wilson sisters (think Paris and Nicky Hilton), who may be targets for a kidnapper. They are on their way to a weekend at the Hamptons where they hope to be photographed for the cover of a magazine. A minor car accident on the way there leaves them with scratches on their faces and they refuse to be seen that way. So, the Copelands call in the FBI’s crackerjack undercover make-up team to transform them into the Wilsons. Conveniently, they both already have earrings.

Despite the fact that they are taller than the girls and the latex masks applied to their faces make them look like victims of Botox overkill, no one in the Hamptons seems to notice anything significantly different about “the girls” (one friend guesses that they’ve had collegen treatments to turn their lips from “Cameron Diaz to Jay-Z”). The Copelands squeal and giggle, shop with the girls, go all mean girls on the snooty rich snobs, and participate in a fashion show and a dance-off (okay, that dance-off is pretty funny). They also go out on dates, Marcus in drag with a smitten athlete (the very funny Terry Crews) and Kevin as a man but pretending to be someone else to impress a pretty reporter.

Gender and race-switching are inherently funny but the situations and jokes in this script do very little to build on that energy and sometimes actually get in the way. There are predictable culture clashes, as when the society girls sing along to Vanessa Carleton’s “1000 Miles” and the Copelands have to pretend to know the words. Then, when the rap song comes on…well, you know where this is going. (A twist on this scene later on provides the movie’s most sustained laugh.) There is a lot of gross-out humor involving various body parts and functions, and some leering double entendres. There are also predictable life lessons as the Copelands develop more empathy for women and encourage the society girls to have more self-respect, to insist on the best for and from themselves. Too bad the Wayans forgot to learn that lesson themselves; the insights are delivered with no more enthusiasm, sincerity, or imagination than the comedy.

Parents should know that the movie has very crude and vulgar material for a PG-13, with comedy based on sexual references (including a game where players have to choose between two unappealing sexual encounters), drug jokes, insult humor, and a lot of graphic potty humor. Characters use strong language, not just the usual “almost-R” words but also terms that may concern parents like “yeast infection,” “coke whore,” “bitch fit,” and the n-word. Racial insults and stereotyping are intended to be comic. The movie has some comic and action violence, meaning that a lot of punches are thrown and a few shots are fired but no one is seriously hurt.

Families who see this movie should talk about what Kevin and Marcus learn from pretending to be white women. Why was it so hard for Karen, Lisa, and Gina to feel good about themselves and their relationships?

Families who enjoy this movie will also enjoy the better movies it borrows from, like Some Like it Hot, which was first on the American Film Institute’s funniest movies of all time, and Tootsie, which was second. They may also enjoy Martin Lawrence in drag as an undercover cop in Big Momma’s House. The freshest and funniest Wayans film is still I’m Gonna Git You Sucka.