Wow, what a load this is. I'm not even entirely sure what it was supposed to be. It was supposed to be funny, I know that much. And it isn't. Here's Danny McBride, James Franco, Zooey Deschanel, Natalie Portman, and Justin Theroux -- in a stoner comedy set in a sword-and-sandals fantasy tale -- directed by David Gordon Green ("Pineapple Express") and from the writers of "The Foot Fist Way" and HBO's "Eastbound and Down" -- and this is what they come up with? Ten thousand penis jokes?

"Your Highness" offers the same kind of disappointment as "Paul" (so much talent, such cheap jokes), yet it's exceptionally lazier. Though clearly very expensive to make, it has the feel of something conceived and shot over the course of a weekend. If you watched a lot of fantasy movies in the early '80s -- "Conan the Barbarian," "Krull," "The Beastmaster," and such -- and got your buddies together, and got really stoned, and for some reason had access to $50 million of studio money, you would make this movie. And no one but you guys would want to watch yours, either.

It takes place on your typical fantasy planet, the kind that closely resembles medieval England but has witches, cyclopses, and other magical creatures. The noble Prince Fabious (James Franco) is handsome and brave, while his brother, Prince Thadeous (Danny McBride), is a coarse, useless pothead. When Fabious' true love, Belladonna (Zooey Deschanel), is abducted by the evil warlock Leezar (Justin Theroux), Thadeous joins his brother on the epic quest to save her. Along they way they meet Isabel (Natalie Portman), a mighty forest warrior who also happens to be a hot chick. From there the plot follows the familiar pattern of perilous caves, magic riddles, mini-quests to obtain special swords, and the like.

You may be expecting a parody of the fantasy genre, but that's not what this is. They play it pretty straight, without meta-references or satire. The joke is simply that even though it looks like a fantasy adventure, and everyone uses archaic words like "thou" and "hast," they also speak in modern vulgarities. Basically, the joke is that it's your usual sorcery movie, but with F-words and a juvenile obsession with sex and sex organs.

And goodness knows there's nothing wrong with juvenile humor! But it has to be actual humor, you know? You have to actually make a joke. By itself, the idea of a guy dressed as a medieval knight smoking weed and dropping F-bombs is only funny for a couple seconds. A well-timed burst of anachronistic profanity, while occasionally good for a laugh, loses its potency when it's the primary weapon in your arsenal.

The screenplay is credited to McBride and Ben Best, but they and the director have made it common knowledge that the bulk of the dialogue was improvised. Yeah, no kidding. Not improvised well, either. As naturally funny as Franco and McBride are separately, they have little comedic chemistry together. They never seem committed to what they're doing, with (intentionally?) half-baked faux-English accents and a reliance on the aforementioned verbal crutches. They're like two cool kids roped into being in the school play who don't mind goofing around but don't want to seem too serious about it. Everyone else is acting; Franco and McBride are pretending to act.

The movie's fixation on phalluses (something else that "Paul" had) should be the subject of someone's thesis paper. It's astonishing how often the "punchline" of a joke boils down to: tee hee, wieners. Fabious' mewling manservant, Julie (Toby Jones), gets stripped naked at one point, and it's discovered that he lacks genitalia completely. And that's it. It doesn't affect the story -- the detail is there only for humor purposes. It's a fine set-up, too. Lots of humor potential in a pitiful character who for some reason has no genitals. Yet the movie doesn't make any jokes about it, and we only see the area in question for a fleeting moment. Why go to the trouble of including this detail if all you're going to do with it is have the other characters say, "Hey, Julie doesn't have a d***!"? It's like they set the ball on the tee and then didn't even bother to swing at it.

That's the movie in a nutshell: lots of effort spent creating a fun environment in which to explore a loopy premise, little effort spent on the actual execution. The supporting cast is better than the leads. Justin Theroux is just interesting enough to steal the show (not that anyone was guarding it); Portman and Deschanel are eager to play along. I won't deny I laughed at a couple gags involving dwarfs and a minotaur. I'd probably laugh a couple times at the movie you and your stoned buddies made over the weekend, too, but that wouldn't make it a real movie.

Grade: D

Rated R, pervasive harsh profanity and vulgarity, a lot of nudity, a lot of graphic violence

1 hr., 42 min.

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