Harold & Kumar in the March of the Toy Stoners

A Very Harold & Kumar 3D Christmas had me at the cannabis-shaped snowflakes. They waft from the screen onto the lenses of stereoscopic glasses. Ordinarily one doesn't encounter this unlikely combination of low comedy, high ideals, and cheesy optical effects outside of a head shop.

With a scene change every 90 seconds and a gag every 15 or so, this third installment of the Harold & Kumar franchise, nearly funny as the first and funnier than the second, succeeds in its heroic quest to leave no stoner unturned. Think of it as Airplane! with controlled substances.

Two nicely mismatched buddies are now estranged. They are the tightly wound Harold (John Cho), an investment banker with Occupy Wall Street protesters surrounding his office, and the loosey-goosey Kumar (Kal Penn), who has a medical degree but failed his drug test. Harold, now married, lives in an upscale Jersey suburb; Kumar, no longer with his girlfriend, still lives in the Hoboken mancave he once shared with Harold. When Kumar exhales, the 3D smoke gets in your eyes.

Hasn't 3D jumped the shark? Harold asks self-referentially. Yes, it has. But as deployed, 1950s-style, in this geek Dean Martin/Jerry Lewis romp with pot and peyote and ecstasy in place of Johnnie Walker, it taps the funnybone. The 3D jokes are reliably funny. But another running gag, the inadvertent exposure of an apple-cheeked toddler to every drug known to slacker, elicits discomfort rather than laughter.

The point of this apparent R-rated pointlessness is that it's Christmas Eve, and Kumar accidentally has incinerated the Douglas fir that Harold's father-in-law nursed from a seedling and brought East from California. Harold needs a new tree. Kumar needs his old friend.

On this night of a thousand drugs, one that involves encounters with tree salesmen pretending to be gangstas, Russian mobsters pretending to be human, and Neil Patrick Harris pretending to be straight, the stickler and the slacker ingest more than the Hangover dudes. And yes, H & K 3D pays a polite nod to that kindred drugathon as well as to A Christmas Story.

How baked do Harold and Kumar get? So baked that during the movie's first hour they turn into Claymation figures. So baked that stoner illogic saturates the film and the nominal heroes are displaced by a 'droid called the Wafflebot, an automaton that looks like it was designed by George Jetson and dispenses waffles and syrup. (Where can I buy one?)

The humor is rowdy, rude, and cheerfully crude, the high jinks mostly inoffensive (albeit massively illegal). Director Todd Strauss-Schulson is good at simulating how those under the influence become helpless observers of the human comedy - much like the movie audience. Two cheers for Harold & Kumar 3D.

Contact movie critic Carrie Rickey at carriedrickey@gmail.com.

A Very Harold & Kumar 3D Christmas

Directed by Todd Strauss-Schulson. With Patton Oswalt, Paula Garcés, John Cho, Elias Koteas, Danny Trejo, Eddie Kaye Thomas, Thomas Lennon, Danneel Ackles, Kal Penn, Neil Patrick Harris. Distributed by Warner Bros. Pictures.

Running time: 1 hours, 29 minutes.

Parent's guide: R (for strong crude and sexual content, graphic nudity, pervasive language, drug use and some violence).