"Dumb and Dumberer: When Harry Met Lloyd" couldn't be dumberer if Harry and Lloyd had written the script themselves.

A cash-in prequel to 1994's guilty-pleasure gross-out comedy starring Jim Carrey and Jeff Daniels as two low-IQ nincompoops on a cross-country trip, this movie is an obtuse, half-assed, meandering, slapped-together, pointless and nearly plotless journey back to the high school days of the same two dolts.

Twenty-something actors Derek Richardson (aping Daniels' blank stare and frazzled Einstein hair) and Eric Christian Olsen (doing a sporadically passable Carrey impression, with the character's bowl haircut and chipped tooth) don't have much to work with as Harry and Lloyd. Having been co-written and absentee-directed by Troy Miller ("Jack Frost"), "Dumberer" has no hint of the low-brow wit of the first movie -- which was the debut of the writing-directing Farrelly Brothers ("There's Something About Mary").

Its one or two laughs (special effects are used to depict the physiological effects of a Slurpee brain-freeze) are lost completely in a nonsensical yet simplistic story, driven by completely feeble expository dialogue. "I think I've finally figured out how to bilk this school out of enough money to buy that condo in Waikiki," says the school's crooked principal (Eugene Levy) to his ditzy lunch-lady lover (Cheri Oteri) before starting a "special needs" program to win a $100,000 grant.

Our dimwit heroes are, naturally, the class's first recruits, followed by an angry punk, a football player, a broken-English foreign exchange student and other Central Casting clichés. But the personality-free Prettiest Girl In School (gaunt but stacked Guess model Rachel Nichols), who is an aspiring investigative reporter, has resolved to expose the principal's scam -- and Harry and Lloyd mistake her subsequent journalistic interest in them as a come-on.

This is the kind of movie in which, for no reason whatsoever, sexy twins in a Ferrari pull up to Harry and Lloyd on the street and invite them to visit their all-girls college -- and it doesn't even lead to a punchline. It's the kind of movie in which telling Nichols that "your milk bubbles look nice" is supposed to garner raunchy giggles.

It's so bad the makeup people didn't even bother making Lloyd's "chipped tooth" look convincing (you can see the black paint in every scene). It's so bad even Levy -- who ran away with every scene in March's otherwise weak comedy "Bringing Down the House" -- isn't funny. Not once. Even the closing-credit bloopers and out-takes are flatliners.

Seeing as the Farrelly Brothers haven't made a good movie themselves since 1998's "Mary," you'd think they'd want to be more careful in selling out their nyuk-nyuk legacy. But then again, since "Mary" was their last good movie, perhaps they know they're washed up and just saw dollar signs. After all, it's readily apparent that nobody involved in this inept debacle cared one iota about quality, originality, common sense or making people laugh.