You should definitely go and see “Step Brothers” if you could hardly wait for another typical American comedy, abounding in lewd and goofy humor and clichés.

It’s like Dumb and Dumber become step brothers and also the dumbest ever.

“Step Brothers” is produced by Judd Apatow and his and Will Ferrel’s manager, Jimmy Miller, but unfortunately, it has nothing of the humor in “Talladega Nights: The Ballad of Ricky Bobby,” which was also produced by the two.

It seems the filmmakers found the idea of two men who never grew-up, who are 40 years old and still live with their parents, funny. Well, you can be sure the parents of such men in real life would not at all be amused.

We’ve seen so many successful American comedies featuring teenagers, so why shouldn’t we enjoy a new one, with grown-ups acting like teenagers?

The protagonists are Brennan Huff, played by Will Ferrell, a thirty-nine-year-old who has never left home and lives with his divorced mother, and Dale Doback, played by John C. Reilly, a forty-year-old who has also never left home and lives with his widower father.

The two man-boys both think greatly of themselves, while eating chips in front of the television. Brennan considers himself “the songbird of his generation,” although he does not have the guts to sing for an audience since his evil younger brother Derek (Adam Scott) humiliated him by chanting “man-gina” together with his buddies while poor talented Brennan tried to perform in their high school musical.

Dale likes to think he is an expert drummer and he also claims to manage a fantasy baseball team.

Brennan once had a job at the pet store, which he lost. Dale has never been employed.

The two “children” are happily living off their parents’ backs, until their parents, Nancy Huff (Mary Steenburgen) and Dr. Robert Doback (Richard Jenkins) meet, fall in love, marry and…disaster! move into Robert’s home. Which means their poor sons are forced to live together in the same room as step brothers.

Obviously, Brennan and Dale hate each other at first sight, but, before you start pitying them, they actually find out they are so much the same, so they become best friends. And here the fun part is supposed to start. The “fun” involves as follows: testicles, vomiting, bathroom activities, nudie magazines, dog poop, the discovery of the opposite sex at the age of 40.

And then the fun is over, when the men-boys’ parents decide to get divorced and also to kick their children out. This change forces the two dumb “kids” to grow up, face reality and find a job. Which is also supposed to be funny.

The very few amusing moments of the movie are suffocated by vulgar, gross-out humor and the two brats’ guffaws.

“Step Brothers” is rated R (Under 17 requires accompanying parent or adult guardian).

Directed by Adam McKay
Written by Will Ferrell and Mr. McKay, based on a story by Mr. Ferrell, Mr. McKay and John C. Reilly
Director of photography: Oliver Wood
Music by Jon Brion
Produced by Jimmy Miller and Judd Apatow
Released by Columbia Pictures.