"Friends With Benefits" is a savvy, satirical date movie that holds the conventions of romantic comedy up to self-aware spoofing while still delivering the goods.

Justin Timberlake steps into his first leading role with a winning air of ironic self-consciousness. As the woman who agrees to be his no-strings-attached bed buddy, Mila Kunis has a flash, fire and humor that is scarce among young actresses. They are enormously attractive actors with a strong current of romantic electricity running between them, and they make the film a swell night out, especially for couples who love to laugh.

The story examines the hypothesis, often postulated but rarely tested, that men and women can have a healthy sexual relationship without all the sticky emotional glue that usually accompanies grownup sleepovers. Timberlake, the new art director for GQ magazine, and Kunis, the corporate headhunter who got him the dream job, put it to the test. They like each other immediately but each comes with a considerable amount of emotional baggage. They agree that sex is a pleasant stress-reliever, like cracking your neck or a game of tennis.

After a few jolly, raunchy booty calls, guess what: The theory begins to disintegrate. A sweet, tentative feeling grows between them, etc., complications ensue, etc. Questions of commitment arise, only to be wrestled to the ground with brusque jokes.

But they recur, chasing our heroes like mutant zombies until the inevitably happy finale.

The gravitational pull of the time-tested story line is strong, but the movie is fueled with enough creativity to achieve liftoff. The filmmakers respect the movie tradition they're working in. They may mock it but they never condescend to it.

A gallery of well-known actors turn up in tiny, smart cameos that ought to remain surprises. Patricia Clarkson plays Kunis' mother and Richard Jenkins portrays Timberlake's dad, bringing idiosyncratic human interest to what could have been throwaway roles.

Movies such as this live or die by their stars, and here the casting is very fortunate. Timberlake isn't a dreamboat leading man in the old Rock Hudson mold of stolid masculinity. He's more a Tony Randall type, wry and bantamweight, dancing nimbly on the tightrope between comedy and romance. He sings occasionally but he doesn't belt it out, crooning in an ordinary, happy voice that would hold its own at a Wednesday night karaoke competition. Kunis, who has dark, beckoning eyes and a smoky voice made for caressing punch lines, plays her role at cruising speed. Other than a couple of passages where she is called on to sulk, she confidently holds the screen and involves us in her character.

The actors make intelligent jokes about how movies have ruined romance, and they rip to shreds a dire-looking Jason Segal date movie that embodies every cloying cliché of the type. They also make unflattering jokes about T-Mobile, HBO, Barnes & Noble and Nicholas Sparks that -- for once -- I don't think represent product placement. These are smart people saying smart things, which is what comedy should be.

From the opening, which uses a switcheroo from "The Silence of the Lambs" to pull the rug from under our expectations, to the zippy little kicker after the end credits, there's scarcely a scene that lacks freshness and charm.