'Pineapple Express' (R): (out of four)

The gun thriller meets the dope smoker comedy in "Pineapple Express," a movie that works its humor into the marquee, with a title that could apply to both a runaway train or a specialty breed of marijuana.

Of course, the real definition is the latter. Pineapple Express is the variety of the controlled substance that pot dealer Saul Silver (James Franco) rejoices in dealing out to his favorite customers -- to men like Dale Denton (Seth Rogen), a man who spends his life serving subpoenas to people being sued.

He hates his job and Saul has very little else to do, so both settle in on the couch and light up. They sample the Pineapple Express.

What unfolds from there is nothing short of a high-octane, bloody-and-bruising action film, a thriller worthy of Bruce Willis -- but starring instead two guys so stoned they can't quite see straight, much less put together a comprehensive strategy of self-defense.

The unexpected yin-and-yang proves most hilarious when Saul and Dale find themselves embroiled in a high-speed police chase. Having commandeered a police squad car, its windshield smeared with liquid, Saul tries to play the part of Arnold Schwarzenegger. He punches the gas, but then can't find the lever for the windshield wipers.

Summer Movies: Video, Slideshows, Contests, More

He tries to kick out the window so he can see better, but only his foot punches through, and he is forced to drive with a leg dangling in the air, sticking out of the glass. It isn't until later in the film that Saul, Dale and Red (Danny McBride) -- their absurdly chipper third team member -- reminisce about this high-speed chase, giggling insistently. But we get the feeling that this is how the entire film was written, director David Gordon Green (shifting here from the poetry of such independent films as "George Washington" and "Snow Angels to more mainstream fare) sharing drinks with executive producer Judd Apatow (the man behind such comedies as "Knocked Up" and "Superbad"), and getting more drunk as they imagine the various, absurd episodes they could put Saul and Dale through.

Sure enough, the awkward scenarios continue. Being chased by a drug kingpin who wants them dead, both Saul and Dale learn how to improvise and defend themselves with semi-automatic rifles. Short on money, they turn to a schoolyard in hopes of selling weed to some high schoolers. Running out of ideas, Saul runs to visit his grandmother in the nursing home; Dale, meanwhile, rushes to his girlfriend's house, forgetting all about the planned meeting of the parents and ruining a family meal in memorable fashion.

Just like Harold and Kumar getting high as they look for a White Castle, it's Saul and Dale who make this far-fetched story fall into line with the perfect comedic pitch, Franco plays Saul as a stoner so care-free and benign that he's difficult to judge Rogen, to the contrary, is the guy with the painful job, who stresses out over his high school girlfriend, and who relies on marijuana as a way of letting all go, reverting to the mental state of an adolescent.

While Harold and Kumar were just looking for some late-night eats, Saul and Dale are trying to stay one step ahead of a drug lord who is the midst of a turf war with his Asian counterparts. Dale was accidentally parked across the street when this man set out to kill one such Asian, and seeing Dale flee, the tough guy is now convinced that he is yet another enemy, waiting to move in for the kill.

This is what counts for plot in "The Pineapple Express," but really, none of the details matter. All the peripherals are merely excuses to put Saul and Dale in absurd situations -- complex scenarios involving guns, girls and explosions that lead them to freak out. Heck, even hiding in the forest, trying to stay out of harm's way, the two can't figure out how to destroy their cell phones. Then they get scared of the dark.

Yet we dig it because Franco and Rogen make it look genuinely fun. They wing the martial arts combat, play it fast and loose with the assault rifles, but all of that pales in comparison to the two goofballs smoking up with their new high school customers. As the tunes turn up and the camerawork reverts to slow-motion, "Pineapple Express" stands as a giddy throwback to the '70s drug comedies that were more about whimsy than the gross-out humor of today's PG-13 hits. This isn't a film for kids, that much is certain. But it's also not very offensive. Saul and Dale aren't so much losers as two delusional guys looking to escape their boredom. And while high, they can see themselves differently, as the sorts of guys who could indeed pack some heat and lead an assault on a secret drug factory.

The movie is just as much a fantasy as it is a comedy -- one hilarious fantasy.