Seth Rogen, left, and James Franco star in the comedy Pineapple

Gary Cole, left, portrays a criminal kingpin who teams with a dirty cop (Rosie Perez) to hunt the heroes in the action-comedy Pineapple

Imagine a “Pulp Fiction” starring the stoners from “Knocked Up.” That’s “Pineapple Express,” a riotously funny introduction to a whole new genre of film: the stoner action comedy.

Given its laughs by Seth Rogen, Judd Apatow and friends (think raunchy and pot-centric) and its structure and action beats by indie director David Gordon Green (Undertow), “Pineapple” features fierce and fiercely funny brawls, shoot-outs and car chases. And in between moments of extreme jeopardy, our blissed-out heroes get blitzed. They “torch up.”

Rogen, who co-wrote and stars in this, created a comic exploration of the odd relationship between pot dealer and pot user. He plays the user, Dale, a process server who dons easy disguises to serve subpoenas on the unsuspecting. He’s 25 and dating a high school girl (Amber Heard), something he kind of realizes is inappropriate. When he isn’t stoned.

Because Dale lives to light up. He is dependent on his dealer, Saul (James Franco, hilarious), a guy he barely knows but has to trust, a man he wants to keep on friendly terms, but not to the point of “friendship.” Saul, on the other hand, is lonely. Nobody wants to be pals.

But things change after Saul serves Dale some rare, wilder-than-wild weed, “Pineapple Express,” which he then tests on a cross-shaped joint.

“This is the apex of the vortex of joint engineering. This is what your grandchildren are gonna be smoking!”

Dale blazes up while waiting to serve some papers on a bad guy (Gary Cole, terrific). And he sees the villain and his cop pal (Rosie Perez, born to curse and fire guns) kill a man. That sets off a whole chain of events that tests Dale and Saul’s “relationship,” Dale and girlfriend Angie’s “relationship” and Saul’s “relationship” with his supplier, Red, played to hilarious effect Danny R. McBride, as cluelessly comical here as he was in “The Foot Fist Way.”

The potheads are paranoid, of course. The potheads panic, of course. They just can’t put down the bong long enough to think their way out of this.

And we hurtle along with them on a panic-stricken ride on the “Pineapple Express” as they dodge cops, goofball hit-men (Kevin Corrigan and Craig Robinson), the Chinese mob and Angie’s irate family (Ed Begley Jr. and Nora Dunn). They flee to the woods. They throw away their cell phones and ditch Dale’s car. They need cash, so they sell pot to high schoolers. Yes, this is as amoral as it is funny and violent.

And they light spliffs and do profanity-laced comic riffs every step of the way.

A prologue tips us that the magic weed is the product of a government experiment from long ago and gives room for more supporting players (Bill Hader) to score bonus laughs. Begley and Dunn have just one scene, but they had me on the floor.

Rogen is more comfortable in this leading-man role than he’s ever been. And Franco, long a third or fourth banana, finally finds his voice as an Ethan Hawke on weed, a dazed and ever-confused stoner who loves his Granny and hates talk radio.

If you had trouble keeping your under-age kids from sneaking into “Superbad,” that’s nothing to what you’ll be going through with “Pineapple Express.” This one takes the action comedy to places – irresponsible, violent and funny – that it has never been before.