In theaters

STEP BROTHERS, directed by Adam McKay, written by Will Ferrell and McKay, 93 minutes, rated R.

Adam McKay’s “Step Brothers” is all about using what you’ve got. In this case, what he’s got is a one-joke premise, but McKay milks it with such abandon, the film’s intended audience of 20-something males likely will dig it – even if they’re faced with the truth of their own childhoods while watching it.

Some will recognize themselves in this movie, but take heart; there’s always room to atone, always a chance to right the course. As for those who don’t, here’s a piece of advice. Take your parents to the film and note aloud how lucky they were that they weren’t saddled with this sort of heathen-havoc.

Conversations about your inheritance should ensue.

From Will Ferrell and McKay’s script, “Step Brothers” hails from producer Judd Apatow (“Knocked-Up,” “The 40-Year-Old Virgin”), who has a knack for knocking out the raunchy without losing our affection for his characters in the process.

Since McKay has a more rough-and-tumble approach, the raunch he offers is amplified to the point that nobody is going to accuse him of neutering his film’s rougher edges. This is a movie that literally has cojones. Those who see it will know what I mean.

In the movie, Will Ferrell and John C. Reilly are Brennan and Dale, two 40-year-old men who act like 10-year-old brats, and who’d rather like to keep it that way. They don’t work, they don’t have lives beyond the reach of their sofas, and that’s just how they want it to remain.

Fat chance of that happening. When their single parents (Richard Jenkins, Mary Steenburgen) meet at a convention, fall in love and decide to marry, Brennan and Dale become reluctant, evil stepbrothers. The movie turns ugly when they’re forced to live together, and it all goes south the moment they start to share a bedroom.

Taunts, violence and whispered threats abound, but don’t expect the strife to end when Brennan and Dale become friends. When Brennan’s accomplished older brother, Derek (Adam Scott), appears on the scene to create his own share of trouble, the movie takes its gloves off and starts swinging, particularly when Derek’s wife (Kathryn Hahn) takes a romantic shine to Dale.

In the end, it’s safe to say that this is one of the summer’s meanest movies, which is why it’s so critical for Ferrell and Reilly to infuse their characters with whatever charm they can muster. Like the movie itself, there isn’t much of that to go around (you’ll never look at a drum set the same way again). But by the time the film has exhausted every one of its crude jokes, enough laughs have been wrung from its caustic script to spark its audience to life and to satisfy its core audience.

Grade: B-

On DVD and Blu-ray disc

Overlook the dogs out there – Dana Carvey’s “Squatting Monkeys Don’t Lie,” Heather Graham’s dreadful “Miss Conception” – and it’s mostly a solid week on DVD.

Highlights include the fourth season of “That Girl,” with Marlo Thomas busy swinging her fists – at least figuratively – as one of television’s first feminists. She was that girl Ann Marie, an independent young woman with aspirations to be an actress. Her romantic relationship with Ted Bessell’s Donald remains one of sitcom’s more satisfying relationships – for a time, they were essentially the “It” couple in “That” series. Look for Lew Parker and Rosemary DeCamp in supporting roles.

Also available are two family affairs. “Family Ties: The Complete Fourth Season” follows the familiar ups and down of the Keaton family, with this season focusing on the love brewing between Mallory (Justine Bateman) and Nick (Scott Valentine), not to mention Alex (Michael J. Fox) and Ellen (Tracy Pollan, Fox’s real-life wife).

On DVD and Blu-ray is the adventure movie “Nim’s Island,” with Jodie Foster, Abigail Breslin and Gerard Butler cast in a lively retelling of Wendy Orr’s children’s tale.

In the film, Breslin’s Nim reaches out through cyberspace to an agoraphobic writer (Foster) who comes to her rescue on a South Pacific Island when Nim’s father (Butler) goes missing at sea. Fans of Foster and Butler should note that this is indeed designed for very young children, who likely will grease over the ongoing run of predictable plot points and steep lapses in logic.

On Tuesday, Lionsgate releases two titles on Blu-ray disc, the least interesting of which is Hype Williams’ “Belly,” the 1998 gangsta drama that stars Nas, DMX, Method Man, T-Boz and others in a violent story that has style to spare, sure, but also a disappointing number of racial stereotypes.

Faring better is Oliver Stone’s 1991 movie “The Doors.” At 31/2 hours, it’s far too long of a plunge into that rock group’s meteoric rise and fall, but its saving grace is Val Kilmer’s performance as lead singer Jim Morrison. He peaked with this movie, and hasn’t come close to besting it since.

Rounding out the week are the DVD and Blu-ray releases of the Academy Award-winning “Kiss of the Spider Woman,” which arrives on a comprehensive two-disc collector’s edition filled with extras; the stoner comedy “Harold & Kumar Escape from Gauntanamo Bay,” which uses its sly brand of humor to say plenty about the state of race relations in the United States (really); and the slight, overly sentimental “CJ7,” which hails from Stephen Chow, the man behind the terrific “Kung-Fu Hustle.” If he weren’t co-starring in it, you’d be hard pressed to know he was behind it. This movie has little of the former movie’s unbridled wit and mischief.

WeekinRewind.com is the site for Bangor Daily News film critic Christopher Smith’s blog, video podcasts, iTunes portal and archive of hundreds of movie reviews. Smith’s reviews appear Mondays, Fridays and weekends in Lifestyle, as well as on bangordailynews.com. He may be reached at Christopher@weekinrewind.com.