“Bridesmaids” is a frat boy’s idea of what a funny “chick flick” should be. So, hat’s off to Kristen Wiig and Annie Mumolo for scripting a movie that is a raunchy hoot, that plays to that demographic and yet doesn’t lose its femininity.

This is “Her Hangover,” a smarter and sweeter stumble to the altar that never quite gets to Vegas, and doesn’t seem to mind. Paul Feig directs this to the rhythms of Wiig’s quirky timing, blowing through big, gross gastronomic laughs but pausing for the “My best friend’s getting married and leaving me” moments of self-loathing and panic.

We meet Annie Walker (Wiig) as she’s finishing up a night of unbridled, needy sex with her regular booty call (Jon Hamm). He’s content, she’s struggling not to be clingy. And failing.

“You should go,” he purrs, adding, “I’m going to miss you sooo much.”

Wiig makes Annie’s low self-esteem painful, real and very funny as she adds climbing the guy’s driveway gate to her humiliating “walk of shame.”

Then her best friend since childhood (Maya Rudolph, Wiig’s former “Saturday Night Live” castmate) breaks the news that she’s getting married. Lillian needs a maid of honor. Annie, “are you sure you’re up to it?” She isn’t. But Annie accepts anyway.

Lillian is marrying into money. And she’s become close with Helen (Rose Byrne), the wife of her husband-to-be’s boss. Helen has her own ideas of how the wedding should be, and from the moment she and Annie meet, elbowing each other away from the microphone at an engagement brunch, it’s war. Helen has money and taste and a faintly condescending air. Annie is threatened and overwhelmed. Helen hijacks the wedding, but not before Annie’s bride-and-bridesmaid brunch that leads to the film’s signature scene — women trying on gowns in the middle of an explosive attack of food poisoning.

The other bridesmaids? Melissa McCarthy of TV’s “Mike & Molly” has the portly Zach Galifianakis role here, playing Megan, a gonzo big girl who is both inappropriate and up for anything. Wendi McLendon-Covey is droll and biting as Rita, the bitter blond into her second decade of marriage. Ellie Kemper of “The Office” is the naive newlywed of the quintet. They complain about men and hormonal teenage sons and discover just how little they all have in common.

But this is Wiig’s movie and Annie’s story. We learn of her failed bakery and see her tactless way of warning customers at the jewelry store where she works that “love” isn’t “forever.” Even with BFFs. We meet her AA-addicted mom, who sponsors other alcoholics and wallows in the world of addiction, even though she has never had a drink herself. We see the beat-up car Annie drives and stumble into the awful Brits (Rebel Wilson and Matt Lucas) she is forced to share her Milwaukee apartment with.

And Annie sees all this, too, as she takes stock and realizes the drain her life has spiraled down.

It takes real cunning to build a romantic comedy that plays by femme-friendly rom-com rules — Annie meets Mr. Might Be Right, an Irish state trooper played by Chris O’Dowd — and still manages to hit those “Wedding Crashers”/”Hangover”/”40 Year Old Virgin” notes. There’s even a hint of girl-on-girl action, just for good frat-boy measure.

Wiig, as Annie, is the vortex into which all this is spinning. Annie’s legs are too skinny and her skirts are too short, her hair’s overdone and everything about her screams “single, aging and hating it.” She is a marvelous creation and even as the film’s energy wanes, Wiig keeps her funny and bittersweet, somebody we root for because we think she deserves better despite all the evidence she gives to the contrary.

Film focus

WHAT: “Bridesmaids”

RATED: R for some strong sexuality and language throughout

RATING: 3 stars

RUNNING TIME: 2 hours, 5 minutes

Kristen Wiig, left, and Rose Byrne appear in a scene from “Bridesmaids.”