MOVIE REVIEWS : As Gump’s Momma Used to Say . . . : ‘Stupid is as stupid does’ is an apt description for Jim Carrey and Jeff Daniels in ‘Dumb and Dumber,’ which is very dumb, and also extremely tasteless, silly--and funny.

“Dumb and Dumber” is a heap o’ gags about dumbness. Most of the jokes are dumb dumb but some of them are actually smart dumb. The film seems to have been made for precocious 7-year-olds and their parents--at least the type of parents who stay up to watch “Beavis and Butt-head.”

Bathroom humor isn’t exactly an acquired taste. Either you think it’s funny or you walk. “Dumb and Dumber,” which stars Jim Carrey and Jeff Daniels as two low-wattage buddies, Lloyd and Harry, abounds in potty jokes and gross-out gags. The real joke is that grown men are actually doing this stuff. And Carrey and Daniels go all the way with the ridiculousness; they really get inside the buddies’ euphoric blankness.

Director Peter Farrelly, who co-wrote the grab-bag screenplay with Bennett Yellin and Bobby Farrelly, doesn’t stage the gags particularly well, and a lot of comic payoffs misfire just because the camera isn’t in the right place at the right time. But Farrelly isn’t trying to pull our heartstrings either. He has the good sense to stand back and indulge the two actors’ nutball riffs.

The pedigree for this scattershot, anything-for-a-laugh movie has already been set for a new generation by the “Naked Gun” films, and many others. And, in only his third starring vehicle, Carrey is already such an established comic presence that he holds the audience even when he’s just mugging or making screwy little movements with his mouth.

With his bowl cut and chipped tooth, and his jointless gyrations, Carrey is like a more elasticized Jerry Lewis; he may be the most freakishly cartoonish of all the star comedians (which is why he was so well cast in “The Mask”). Lloyd is a variation on the characters Carrey has played in “Ace Ventura” and “The Mask,” but he’s more triumphantly dim. And Lloyd is never so dim as when he thinks he’s being smart: The spark in his eye is greater than the spark in his brain.

Lloyd starts out as an airport limo driver; his roomie, Harry, runs a canine grooming operation out of his truck, which is outfitted to look like a shaggy puppy. Harry (Daniels) is pretty shaggy himself. He’s unkempt in a blotto kind of way; he’s not concerned with his appearance because he’s not really aware that he has an appearance.

The two guys spend half the movie traveling in circles from Rhode Island to Colorado in order to return a misplaced briefcase containing a fortune in ransom money to a socialite (Lauren Holly) who has stolen Lloyd’s heart. (He took her to the airport and she actually listened to his inane banter.)

Along the way there are run-ins with rowdy roughnecks and cops and a kidnaping team (Mike Starr and Karen Duffy) who think Lloyd and Harry are actually master criminals.

A lot of the movie hinges on this smart-dumb misperception: It’s “Being There” for the kiddies. When both boys take turns romancing the socialite, the film totters into its full tastelessness. Just before his big date, Harry is slipped a bottle of laxative by his jealous friend. Guess what happens? He also sticks his tongue on a frozen ski-lift pole. Lloyd, who is more debonair, accidentally assassinates a snow owl at an endangered species benefit with a popped champagne cork.

“Dumb and Dumber” isn’t exactly the sort of movie you can recommend to people--at least not to people you don’t know really well. But it’s got more laughs than “Junior” or “Speechless”--granted, no great achievement. It also has a love of silliness that isn’t all that dumb.

* MPAA rating: PG-13, for off-color humor. Times guidelines: It includes lots of bathroom humor scenes of people gagging.

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‘Dumb and Dumber’

Jim Carrey: Lloyd

Jeff Daniels: Harry

Lauren Holly: Mary

Teri Garr: Helen Swanson

A New Line Cinema presentation in association with Motion Picture Corp. of America. Director Peter Farrelly. Producers Charles B. Wessler, Brad Krevoy and Steve Stabler. Executive producers Gerald T. Olson and Aaron Meyerson. Screenplay Peter Farrelly & Bennett Yellin & Bobby Farrelly. Cinematographer Mark Irwin; (Rhode Island) Brian Heller. Editor Christopher Greenbury. Bradford Johnson. Running time: 1 hour, 31 minutes.

* In general release throughout Southern California.