In the inaccurately titled “Life of the Party,” Melissa McCarthy follows in the footsteps of Rodney Dangerfield and Bing Crosby, among others, in playing what today is referred to as an untraditional college student. Unfortunately, she fares no better than her predecessors did; the anemic comedy does not earn a passing grade, though one might well cheer when she—and it—graduate and the final credits roll.

Written by McCarthy and her husband Ben Falcone (who also directed), the picture is a wish-fulfillment fantasy about how a long-time homebody finds self-fulfillment by completing her long-delayed college degree after being dumped by her dopey husband. Deanna Miles (McCarthy) is just tearfully dropping off her daughter Maddie (Molly Gordon) for her senior year at Dunbar University when hubby Dan (Matt Walsh) announces that he’s leaving her for snooty realtor Marcie (Julie Bower). After visiting briefly with her parents (Jacki Weaver and Stephen Root), she decides to enroll at Dunbar herself, finishing off the final year she needs to complete her degree in Archeology, an accomplishment that will certainly open up the myriad job opportunities she’ll need to make it on her own. (The choice of fields was apparently made merely to allow Deanna and goofy Professor Truzack, an ex-classmate of hers played by Chris Parnell, to trade bad puns.)

This introductory segment of the movie is pretty pallid, generating few laughs though McCarthy and Maya Rudolph, as her acerbic best friend Christine, work overtime trying to raise a few. From the moment she sets foot on campus, though, the picture turns into a series of comic sketches based on absurd coincidences and incredible implausibility.

So we watch Deanna embarrass her daughter in front of her sorority sisters, until the girl comes around (along with the other members of her crew) to support her mom unconditionally. We then see Deanna get a makeover, and the gals triumphing at a frat party done up in eighties style, where a spruced-up Deanna wins a dance-off against campus mean girl Jennifer (Debby Ryan). But that’s not all: she unaccountably catches the eye of hunky Jack (Luke Benward), and before long the two are having sex in the library stacks.

In other tangents, Deanne tries to bond with her dorm roommate Leonor, a weird girl with a vampire streak that makes her avoid the sunlight. And Deanna suffers a meltdown—quite literally—when required to give an oral report in Truzack’s class (a sequence that goes on entirely too long). An inebriated Deanne and Christine play a game of handball. They also trade insults with Marcie and Dan in a divorce mediation session, and again in a restaurant (where a truly embarrassing revelation occurs—one of the sitcom coincidences scripts like this traffic in). Then Deanna and her sorority pals utterly trash Dan and Marcie’s wedding reception.

And one can’t forget the plot thread involving sorority gal Helen (Gillian Jacobs), who’s a bit older that her sisters because she’d been in a coma for eight years, and became an on-line celebrity because of it. That’s a pretty tasteless bit on its own, but it plays (as does another astounding coincidence involving Leonor) into the big finale, in which singer Christina Aguilera appears as herself.

If all this seems pretty ramshackle, it is. There’s a vaudeville quality to the succession of bits, which is italicized by the fact that all of them drag on too long, a sign of both Falcone’s lackadaisical approach, which overindulges McCarthy’s inclination to mug, and the equally lethargic editing of Brian Olds.

Still, one can’t deny McCarthy’s energy, or the equally no-holds-barred efforts of Rudolph to jazz things up. There are also committed bits by Weaver and Root as Deanna’s parents, though Parnell’s portrait of a dotty professor is bland. The younger actors fare worse; this is a particularly wan group of undergrads, with Jessie Ennis’ clueless Debbie and Ryan’s pouty mean girl especially irritating, though Benward’s besotted Jack is the biggest oddity in the bunch. The technical side of things, including Julio Macat’s cinematography, is okay but unremarkable.

“Life of the Party” struggles to make good on the title, but its slapdash mixture of frantic farce and gooey sentiment proves another McCarthy misfire.