Brittany Snow plays a sex addict/sex columnist who drags a guy she just met on a cross-country “revisit every place I’ve had sex” romp in “Hooking Up.”

Which is as crude as it sounds, and a description that works for about half of this generally unamusing road trip romance.

It’s the film’s attempted pivot into seriousness, after making light of sex addiction and –oh — the guy’s reluctant “bucket list” participation in all this before taking one last shot at treatment for his testicular cancer, that the degree of tone deafness the screenwriters suffer from becomes obvious.

“Pitch Perfect” Snow is Darla, whose craving for coitus has her grabbing a quickie in an elementary school classroom on her way to a “Managing Your Sex Addiction” support group meeting down the hall. Her partner? You guessed it, the guy running the group.

Sam Richardson (“Veep”) is Bailey, the support group seeker who stumbles into the wrong room. He’s busted up, at 30, over losing his high school sweetheart (Anna Akana) because, he believes, she is turned off by the testicle-free future.

Darla’s brusque, remote and flippant about everything — her court-ordered support group, sex with an intern on the boss’s desk (Jordana Brewster). After all, her Atlanta magazine column makes her “the Oprah of orgasms! EVERYbody gets one!”

It isn’t concern for her well-being, the perverse idea of an addict writing a column that feeds her addiction, that gets her fired. “Your stories lately just aren’t worth fighting for.”

So she bum’s-rushes Bailey into taking a trip with her. The support group gave her a map as a means of documenting her sexploits and perhaps making amends. She’ll use that map to retrace her steps, reenact her couplings and give Bailey a little dose of what Mr. “One Woman Man” has been missing.

That tacky tale barely holds your interest, even if Snow goes at this with a kind of bug-eyed mean-girl-turned-mean-woman gusto. “This one’s a predator,” as Bailey warns off one guy.

Richardson ably plays the straight-man role in this comic couple, the mopey “All my sexual history could fit on a bar napkin” sidekick and less-than-eager-“assistant” in this stunt that Darla hasn’t told him will make it into a blog and probably into a magazine.

The “Sex Trip” part of the picture never for one second feels giddy, although the stars give it their best in service of screenwriters who can’t manage any better.

But stopping to see Bailey’s parents (Vivica A. Fox and Bryan Pitts), stumbling back into the ex and taking stock of what’s really been wrong with his life turns the picture into something just as dissatisfying, but supposedly serious.

We also get a load of Darla’s gene pool (Amy Pietz, making a mark), too.

A politically-incorrect comedy about sex addiction isn’t the freshest idea, but at least that one had some possibilities. Darla, opening the map in the ancient Cavalier convertible she’s bought for the drive, looking at an “X marks the spot” covered map and catching Bailey’s dismay.

“You’re either judging me or under-ESTIMATING me!”

The limp start and depressed finish make “Hooking Up” a sex comedy in which you can like the cast even as you give up on the movie. Early.

MPAA Rating: R (for sexual content and language throughout)

Cast: Brittany Snow, Sam Richardson, Jordana Brewster, Vivica A. Fox, Amy Pietz and Anna Akana

Credits: Directed by Nico Raineau, script by Nico Ranineau and Lauren Schacher. A Saban Films release.

Running time: 1:43