Your Highness

Directed by David Gordon Green. Starring Danny McBride, James Franco, Natalie Portman, Zooey Deschanel, Justin Theroux, Charles Dance, Toby Jones 16 cert, gen release, 102 min

Your Highnessis a shambling but undeniably funny stoner comedy, writes DONALD CLARKE

WRITING ON Salon.com, Andrew O'Hehir, a grown-up film critic, recently asked: "Is Your Highnessthe worst film ever made?" Any notion that O'Hehir might be on to something was, for this writer, soundly trashed when I laughed out loud at three vividly described examples of the film's supposed awfulness in O'Hehir's review.

This probably suggests that one of us is a bleeding idiot. Given that a sample incident involves Danny McBride wearing a Minotaur's penis round his neck, O'Hehir can probably stand down the lawyers. Me think Your Highnessfunny film!

Still, there's no denying that there is a great deal of slumming going on here. Few directors have followed such a peculiar career arc as David Gordon Green. A decade ago, Green, after releasing a gorgeous, ponderous film called George Washington,was installed as the future of American arthouse cinema. Further acclaim greeted All the Real Girlsand Undertow.

Since then Green has made Pineapple Express, an agreeably moronic stoner comedy set in contemporary America, and Your Highness, an agreeably moronic stoner comedy set in . . .

Well, where exactly? At times, we are in medieval England. At others, the adventures seem to be taking place in Terry Pratchett's Discworld. For most of the film's duration, however, the action plays out in the THC-ravaged outer lobes of a flunking undergraduate's misused brain. It's rather as if Ingmar Bergman moved straight from Personato Stop! Or My Mom Will Shoot.

In tribute to Northern Ireland, where the film was shot, the mythical location has been named the Kingdom of Mourne. James Franco takes time out from his PhD studies (more slumming) to play a suave, gallant prince named Fabious.

Following that lazy Oscar performance, a fug of complacency still hangs around Franco, but Your Highnessreminds us that he understands the rhythms of broad comedy. A little bit Errol Flynn, a little bit Flash Gordon, Franco's Fabious makes a dazzling nuisance of the hero. One can easily understand why Thadeous (Danny McBride), his fat, stoned brother, resents him so much.

After a portion of War of Warcraftchatter, the two brothers set off on a dangerous quest. Fair maiden Zooey Deschanel (slum, slum, slum) has been kidnapped by a sex-mad wizard and they must rescue her before "the f**kening" begins.

Your Highnesslooks and sounds a little bit like The Princess Bride. Mind you, 2001: A Space Odysseylooks and sounds a little bit like Attack of the Alien Slab Monsters. More than anything else – more even than Cheech and Chong's The Canterbury Tales– the picture suggests the work Mel Brooks delivered when he was in transit from magnificent clown to water- treading embarrassment. It's not as good as When Things Were Rotten, Brooks's forgotten TV series, but it's a little better than the great man's History of the World Part II.

The best and most frequently used joke has to do with the anachronistic transplanting of marijuana culture to a world of silvered helms, bloodied broadswords and fluttering damsels. Your enjoyment of Your Highnessprobably depends on your tolerance for people in chainmail saying "f**k, yeah" while chewing on roasted boar bits.

Happily, McBride, whose co-writing duties can barely have exhausted an afternoon, proves just the man to extract humour from flogging a horse that was gathering flies months before the film crew arrived at the Giant’s Causeway. His slovenly, red-eyed truculence is a lazy pleasure throughout.

In short, Your Highnessdoes everything you'd expect from a stoner comedy. Jokes extend themselves well beyond the length any non-medicated audience could bear. Creative stupidity is everywhere about. The bagginess and disorder are essential parts of the hemp-fuelled aesthetic.

The worst film ever made? Heck no. Chill out, sire.