Heathers the Musical at PacRep proudly earns R rating.

The teen movie earned its own genre in the 1980s, thanks to hits like Breakfast Club, Pretty in Pink, Ferris Bueller’s Day Off, River’s Edge, The Lost Boys, Taps, Less Than Zero and Karate Kid.

But Heathers, released in 1988, came out of nowhere, with acidic meanness and merciless satire. It was such a smart piece of work it zipped by theatergoers (did it ever play theaters?) and landed in the VCRs of knowing teens and young adults as a cherished cult classic.

In 2010, Laurence O’Keefe (Legally Blonde: The Musical) and Kevin Murphy (Reefer Madness) decided to give Heathers a go as a stage musical. And they nailed it. That’s how Heathers the Musicalfound its way to Golden Bough Theatre.

Big ups to PacRep. It’s a wicked number, delivered as a red-light-warning Rated R, leaving the profane one-liners and subject matter intact. (The leading female characters alternate actors throughout the run.)

Westerburg High School in Ohio is like most high schools. It’s got its cliques and outcasts, jocks and nerds. Here’s how the kids describe the environment, shouted in song: “Freak! Slut! Burnout! Poser! Short-bus! Cripple! Homo! White trash!”

Smart and earthy Veronica Sawyer (Mia Pak, Katie Hazdovac) grew up with many of them and asks aloud to her diary how they went from happy little kids playing tag and chasing each other to this “Thunderdome” of fear and loathing called high school.

“Martha has a big heart,” Veronica tells us of her friend Martha Dunnstock (Velvet Piini, sweet and vulnerable). “Around here, that’s not enough.”

But Veronica isn’t above the game. She uses her deft writing skills to ingratiate herself on the graces of the three reigning girls on campus: socially anxious Heather McNamara (Maddie Jewell, Natara Denga), bulimic Heather Duke (Niki Moon, Nicole West) and “mythic bitch” Heather Chandler (Gracie Navaille, Jill Miller). Collectively called the Heathers, they are feared and revered for being rich, hot and cruel, alpha cats who control the yard in their high school.

“For a greasy little nobody, you do have good bone structure,” Heather Chandler tells Veronica.

The musical is rife with arrows zinging to and fro, in the dialogue and in the clever songs. They’re organized by a plot line that starts in realism, but gets surreal and deadly real fast.

Heather Chandler, accepting Veronica into their clique on a trial basis, insists she write a fake love letter from asshole jock Ram Sweeney (Dale Thompson) to Martha, who’s had a crush on him since kindergarten.

She does it, but is admonished by a trenchcoat-wearing, Baudelaire-quoting new kid, J.D. (Mickey Perdue). His flirting with Veronica draws the ire of Ram and fellow bully jock Kurt (Ty Barret). The three boys fight, in cool slo-mo, with Kurt slowly crashing to the ground with cartoonish violence. The lighting and sound design really animate the sparsely furnished stage.

When Martha (cruelly nicknamed Martha Dumptruck) shows up at a Heathers party looking for Ram, Heather Chandler sings “Showing up took some guts. Time to rip ‘em out.”

Veronica, drunk, sticks up for Martha: “What’s your damage, Heather?” Then throws up on Heather Chandler and gets kicked out of the inner circle. With teen over dramatization, she considers herself a “Dead Girl Walking” but with little to lose, sneaks through J.D.’s window for some late-night action. It’s explicit but not freaky, a little too bump-and-grind skillful for high schoolers (I think).

The couple go to Heather Chandler’s house so Veronica can beg forgiveness. Instead, J.D. tricks Veronica onto a slippery slope leading to dark places.

When a drunk jock grabs Heather Duke and starts dry humping her at a party, despite her protests, Veronica distracts him off her. Heather Duke gets up and flips off Veronica and tells her “I didn’t need your help.” Veronica looks at the finger and says, “That’s okay, Heather. I don’t need to throw up.”

The subtext is that these teens are in pain. Ignored or bullied, they turn on each other. On a social level, Westerburg High is an animal kingdom. Except it’s not every species for themselves, it’s every individual for themselves.

How to escape such a scary biosphere? Humanity. Pak, as Veronica, delivers it with poise, with humor, with compassion and a dash self-effacing geekiness. Even among a stellar cast – Perdue is cool and intense, Navaille cold-blooded, Jewell is fragile and scared, Moon plays it simmering, D. Scott McQuiston nails several adult roles – she’s a standout. She and Martha are the warm center of a story that’s otherwise emotionally fraught.

But that stuff is packed into merrily irreverent songs like “The Me Inside of Me,” “My Dead Gay Son,” and the sentimental “Kindergarten Boyfriend,” making Heathers the Musical a complex thing for a teen musical. You don’t leave just feeling one thing, but a few things. Teens were in the audience, maybe teens who identify with some of the characters? The line where Heathers is laughing at them, or laughing at the conceits around them, is blurry. In a good way.

HEATHERS THE MUSICAL runs 7:30pm Thu-Sat; 2pm Sun; til Feb. 28. Golden Bough Theatre, Monte Verde Street between Eighth and Ninth, Carmel. $12-$25. 622-0100, www.PacRep.org