Just a couple of weeks after Sucker Punch lulled audiences into stupefaction with its video-game aesthetic and faux female empowerment, here comes another mostly brain-dead genre mashup that just can’t feature enough explosions or barely clad actresses. The difference this time is that the early adolescent males that Your Highness targets likely won’t be bothered to look up from their phones long enough to notice.

The idea seems to be something along the lines of an R-rated The Princess Bride by way of Cheech and Chong, with anachronistic cursing and all the blood, gore, and T&A that one could ask for. The actual result is a sputtering and vastly pleased-with-itself piece of work that resembles something sketched out on the back of a napkin at the end of a very late night and then filtered through the tired grey matter of a few joke-grinding rejects from National Lampoon. It makes David Gordon Green’s last film, Pineapple Express—with which it shares the delusion that simply aping genre tropes, whether it’s bad action or fantasy flicks, suffices as satire—seem almost masterful in comparison.

The co-writer and star of this disaster is the vaguely ubiquitous Danny McBride. He should have been able to hit an easy home run as Thadeous, a lazy and cowardly prince of the kind of fantasy kingdom that doesn’t exist beyond its castle walls. His nemesis and brother, Fabious (James Franco, trying as hard as he can to make this all seem fun), is the sort of guy who’s always riding into the great hall with his heroic hair a-swinging and biceps a-bulging, having just defeated another vicious monster or evil knight.

When the film opens, Fabious not only rides in with the head of a slain monster to display, he also comes bearing a beautiful fiancée, Belladonna (Zooey Deschanel), who had been locked up in the tower of the dread wizard Leezar (Justin Theroux). Unfortunately, Leezar shows up in the middle of the wedding with a trio of evil witches, and many zaps and blasts of magical lightning later, absconds with Belladonna again. Fabious and an extremely unwilling Thadeous ride off to the rescue.

The film that follows is not very funny, but it is fiercely determined to be bawdy, offensive, and oh so dirty. Notice all the modern-day four-letter words the actors spew in their standard-issue fantasy-film pseudo-British accents, not to mention the dreary pot jokes (not as many as you would imagine, based on the title), heaving bosoms straight out of a Playboy cartoon, molestation humor, and buckets and buckets of blood. Certainly, there are fights galore, and a far-too-large budget (whatever it was) blown on beside-the-point special effects that do their best to drown out the occasionally funny double entendre that viewers might cling to, desperately, out of boredom, if nothing else.

Your Highness momentarily snaps into shape when Natalie Portman shows up, as a lithe dealer of death who joins the brothers on their quest. She plays her character straight down the line, instead of weakly mugging or overselling every line, as a too-laidback McBride incessantly does. Where the normally reliable Theroux is stuck clowning with funny teeth and a clownish hairdo, Portman strides across the (admittedly beautiful and appropriately mythic) Irish countryside like some Amazonian warrior princess. If the dull, scattered screenplay had some wit to it, a few jokes appealing to anybody out of middle school, Portman’s cool demeanor would have made her the perfect foil for Franco and McBride’s buffoonery. As it stands, she looks like she’s trying to find her way to a real film.