I have never seen a “last party” teen romp as violent at “The Crusades,” a would-be coming-of-age comedy that drowns in a hot tub of toxic testosterone.

It opens with a teen-planned/teen-featured cage fight and climaxes wtih a gang brawl that should have put victims in the hospital. And that’s after the parade of punchouts that preceded it.

Hard to get happy watching this one. The throwback “Catholic schoolboys fighting rival Catholic schoolboys” story feels like a how-gangsters-are-made drama from an earlier era.

The lusting for the “hot teacher” and clumsy scheming to seduce the all-girls-school coeds are straight out of “Porky’s” and its “Lampoon” era contemporaries.

The amusingly bluff adults — veteran tough guy Mike Starr as a poop-bag-fire on the porch prank victim and Nicholas Turturro as the macho dope of a coach — get most of the few funny lines.

“I just got my PERIOD hearing that!”

But even though the action is well-handled, the Big Party chaotic and cut with brio, “The Crusades” is a singularly joyless affair where the guys fight their way to “manhood” and the girls can’t bully them out of their myopia.

Our Lady of the Crusades is one of two Catholic boys’ schools in town. St. Matthew’s is the other. They are blood rivals, not just in sports.

Pals Leo (Rudy Pankow of “Outer Banks”), Sean (Khalil Everage of “Cobra Kai”) and “extreme senior” Jack (Ryan Ashton of TV’s “School for Boys”) aren’t the toughest, smartest or most popular lads in their “Lord of the Flies” high. They’re just bonded for life to survive.

If the two-fisted nonsense and more mature but bullying Mean Girls from the local Catholic girls school aren’t enough to contend with, encounters with the most savage kids of St. Matthews never end well.

Jack, nicknamed “the Bull,” is a lunkhead always on the verge of getting kicked-out, egged on into violent tests that he delusionally figures he can win. Because of his “bull” headedness.

Leo takes Italian tutoring from the hottest teacher (Anna Maiche) in “The Crusades.” He crushes on her, and on the almost-as-unattainable Ryan (Ashley Nicole Williams of TV’s “Motherland”).

Sean has a serious girlfriend (Indiana Massara), who is seriously peaved at his immature “bros before ‘hos” attitudes. He’s always hanging with the boys, hopeful about “that first time” with Jess, just as long as his bros don’t have something planned instead.

Our Lady of the Crusades is financially strapped, so they” have to merge with the equally hard-up St. Matthews. More competition for dates, more violence, and Jack’s probably facing expulsion over that cage fight that opened the movie.

There’s nothing for it but to put everything they have into this weekend’s school “social” dance with the girls from their sister academy, and then in the drinking and hooking-up makeout “last party” afterwards.

Blaine May makes a perfect “psycho ex boyfriend” looking to bust up Leo over what he imagines is happening with Ryan. Vince doesn’t travel alone. He’s got his own “wrecking crew.”

Over the course of that long night into next day, “The drink will flow and blood will spill,” as the song goes, as The Wrecking Crew keeps pursuing Leo and his mates.

The acting isn’t bad. But no, nobody here is the most convincing “high schooler.” The direction is solid, punchy. Yet the picture isn’t so much plotted as given a time frame to squeeze a lot of fistfights into. The pranks are ancient, the girl characters barely given a function and the laughs few and far between.

It’s as if “The Crusades,” directed by one guy and scripted by him and two other guys, suffers from the same affliction as its characters — “testosterone poisoning.” There was nobody involved in the production to tell them how uninteresting this “story” is and that a “comedy” this angry and violent, and not in a funny way, was never going to play.

Rating: unrated, very violent, teen drinking, sexual situations, profanity

Cast: Rudy Pankow, Khalil Everage, Ryan Ashton, Indiana Massara, Blaine May, Ashley Nicole Williams, Anna Maiche, Nicholas Turturro and Mike Starr.

Credits: Directed by Leo Milano, scripted by Shawn Early, Jack Hussar and Leo Milano. A VMI Release.

Running time: 1:41