Dumb and Dumberer’s problems are many, but, first and foremost, it’s a prequel. 

Such rotten films already come with the inherent stink of cheapness by no longer being able to afford the original talent. And aside from Indiana Jones and the Temple of Doom, which didn’t even really tout itself as a prequel, all of them are turkeys.

Here, there’s no Jim Carrey, no Jeff Daniels, no Farrelly Brothers, no laughs … OK, six laughs. But in addition to lacking the weird-genius pairing of Carrey and Daniels, this film lacks the heart that actually connected audiences to Harry and Lloyd in the first place.

Instead, we’re (sort of) flashed back to 1986. The characters wear stonewashed jean jackets and Zubaz, but the new Pepsi logos, modern slang and Good Charlotte on the soundtrack scream new millennium. Perhaps the only true joy to be had from Dumb and Dumberer is finding where period continuity got thrown out the window.

Insofar as there is a plot, it’s that high-school students Harry (Derek Richardson) and Lloyd (Eric Christian Olsen) find themselves pushed into the “special needs” curriculum. Of course, it’s all a grant-stealing scam perpetrated by the school’s principal (Eugene Levy). 

He’s looking to steal the funds given to the school for having a special-needs class and run off to Waikiki with his lunch-lady paramour (a mildly amusing Cheri Oteri). But as Harry and Lloyd both fall for a comely reporter for the school paper, they inadvertently help to bust the scam wide open.

Something bad happens to co-writer / director Troy Miller any time he strays from TV work. The man behind the camera for the wickedly hysterical HBO series Mr. Show also has 1998’s Jack Frost (a dead Michael Keaton reincarnated as a snowman) and, now, this to his discredit.

Basically, it lifts the playbook from Dumb and Dumber (fantasy sequences, slow-motion montages and putting Harry in the bathroom again) with none of the laughs. Its “original” gags, gay and Chinese jokes among them, are just as dead on arrival, as are the extended bits about the intricate, no tag-back rules of tag and Slurpee-tinged drool. 

Still, there are a handful of moments to cherish, even if they are fleeting. Bob Saget makes a chuckle-worthy cameo, and Oteri gets a couple good laughs as the murder-obsessed lunch-lady. But if projects like this are indicative of her post-Saturday Night Live work, she shouldn’t have left.

Although his shtick gets old fast, there are good laughs that come from Olsen, who has a scary read on Carrey’s facial movements, body language and speech patterns. It’s far from high art, but it is truly funny when he sings Grandmaster Flash’s “The Message” on a mix-tape and tells a vindictive convenience store clerk it’s “on like Donkey Kong.”

Early in the movie, a spiky-haired punk tells a Chinese exchange student, “There’s nothing more American than doing nothing and getting away with it.” Given this supposed comedy as evidence, there are no truer words.