Grade: D

If you’re looking for the highest ratio of jokes about urine, excrement, flatulence, nudity and weed to overall running-time in cinematic history, this sequel to the 2004 buddy comedy may well fill the bill. (The fact that it’s gotten an R rating from the MPAA is absurd but not unexpected.) Your enjoyment of “Harold and Kumar Escape from Guantanamo Bay” will also be enhanced if you watch it stoned. But non-potheads, even those who liked the “White Castle” original (which was, after all, goofy and raunchy but smart), may have trouble with this dumb, rather nauseating follow-up.

The script by Jon Hurwitz and Hayden Schlossberg, who also take over directing chores from Danny Leiner this time around, takes up immediately after the close of the first movie as our heroes return home to clean up and pack for their trip to Amsterdam, where Harold (John Cho) hopes to reconnect with hottie Maria (Paula Garces). In the airport they happen on Kumar’s ex-girlfriend Vanessa (Danneel Harris), who’s now engaged to Colton (Eric Winter), the politically up-and-coming golden boy she’s engaged to marry—and whom Kumar despises.

But their real troubles begin when Kumar tries to light up his “smokeless” bong on the plane and he and Harold are arrested as terrorists and trundled off to Guantanamo Bay. It doesn’t take them long to escape, make their way back to Miami and begin a drive to Texas, where they hope that Colton can clear them. They have a smorgasbord of adventures along the way, involving such varied characters as a family of inbred rednecks, the Ku Klux Klan, President Bush, and, inevitably, a whacked-out Neil Patrick Harris. And they’re persistently tracked by doofus Homeland Security chief Ron Fox (Rob Corddry). Need I add that everything turns out well for the boys?

There are a few scattered witticisms scattered through “Guantanamo Bay,” but for the most part the movie is a flat farrago of full-frontal nudity (both male and female), drug humor, and scatological gags—endless scatological gags. Some of what happens is anti-PC, but in a supremely juvenile way (as in a bit involving two of the duo’s Jewish pals); some might be mistaken for political satire (the stuff about Fox and Bush), but is just puerile nonsense several levels below the worst Mad Magazine offal.

The entire mixture is really unpalatable, and it’s made even worse by the coarsening of the lead characters, who were hardly sophisticated to begin with. The worse effect is on Kumar, who’s been turned into such an obnoxious boor that it’s almost impossible to root for him to win even against such a slick scumbag as Colton; and Penn, who was so subtle in “The Namesake,” plays him much too broadly here. Matters aren’t quite so bad with Harold, who’s less irritating and is played with at least some restraint by Cho. Or maybe he just looks restrained beside the awful Corddry, who looks more and more like David Koechner without the twisted mouth and makes him look positively sedate. Harris goes to extremes, too, but that’s supposed to be the joke. A pity it isn’t very funny. Everybody else mugs ferociously in tune with Hurwitz and Schlossberg’s free-for-all direction, beside which even Leiner’s mediocre skills may be fondly remembered.

“Guantanamo Bay” doesn’t look particularly good technically; perhaps the studio remembered that the original pretty much tanked at the boxoffice, only becoming a cult hit later on video, and—realizing that adolescent tastes are fickle—might have decided to spend as little as possible on the sequel. That might have been a wise decision. After the haze wears off, fans might just conclude that while “White Castle” was a good place to visit, “Guantanamo Bay” is one to avoid.