Man-boys are all the rage at the multiplex. From The 40 Year Old Virgin to Role Models, Hollywood comedies these days feature more arrested adolescents than summer camp. Four of the people most responsible for the increase -- producer Judd Apatow, director Adam McKay and stars Will Ferrell and John C. Reilly -- take things to an extreme in the riotously funny and patently absurd Step Brothers.

Unlike most man-boy flicks, Step Brothers makes no obligatory tug at the heartstrings. There are no overtures to sentimentality or emotional resonance. We're not even asked to feel much sympathy for the protagonists, although their sheer helplessness does elicit some fondness. Fans of Anchorman: The Legend of Ron Burgundy and Talladega Nights: The Ballad of Ricky Bobby know what to expect. McKay and his merry men and women keep the atmosphere loose, improvisational and resolutely vulgar, with outrageous characters saying and doing outrageous things.

Dr. Robert Doback (Richard Jenkins) and Nancy Huff (Mary Steenburgen) meet at a medical conference, make eye contact and quickly wind up in a hotel bed. He is a widower; she is divorced. The couple's mutual lust blossoms into love, however, when they discover that both of them have middle-aged, unemployed sons living at home.

Robert and Nancy marry, a union that causes sudden upheaval for the comfortable lives of Nancy's 39-year-old son, Brennan (Ferrell), and Robert's 40-year-old son, Dale (Reilly). To say that both men are spoiled, overgrown boys is putting it mildly. Brennan is a pouting mama's boy who demands "fancy sauce" (ketchup and mayonnaise mixed together) on his chicken nuggets and whose prized possession is a samurai sword autographed by American Idol judge Randy Jackson. Dale is more abrasive, a self-styled karate expert who brags to his new stepmom that he manages a baseball team -- fantasy league, of course.

Brennan and Dale take an immediate and intense dislike to one another. Dale puts Brennan on notice to keep away from his cherished drum set, a warning that only tempts Brennan to do just that. There is a subsequent fight in which certain body parts are rubbed defiantly on the drum skins.

A treaty between the two comes only after a dinner with Brennan's cocky older brother Derek (Adam Scott) and his family. Derek is an insufferable prick, but Dr. Doback is charmed by his professional success. It doesn't take long before Dale punches Derek in the face.

The move brings Dale and Brennan together -- not to mention Dale and Derek's mistreated, sexually repressed wife, Alice (Kathryn Hahn) -- and the stepbrothers quickly become best friends. It helps, too, that they learn they have so many things in common, including favorite dinosaur (Velociraptor) and favorite non-porn magazine for masturbating ("Good Housekeeping").

The supposed storyline involves Dale and Brennan's hapless attempts to get a job after they are told that they will have to move out of the house and support themselves. Plot is of secondary importance here. The hilarity of Step Brothers, and it is often hilarious, stems from how Dale and Brennan maintain their almost pathological immaturity and self-absorption. Only gifted adlibbers are able to hold their own in a McKay movie, and the group assembled here is masterful. Ferrell and Reilly are the main attractions, of course, but most of the cast members get their chance to shine.

You might hate yourself for laughing as much as you do, but laugh, you will. Of course, one's appreciation for Step Brothers is contingent on one's tolerance for unmitigated silliness. But if you enjoy people making inappropriate and foul-mouthed comments, sly pop culture references, well-executed physical comedy, jokes about masturbation and an a cappella version of "Sweet Child o' Mine," have I got a movie for you.

Fans of the flick will be happy to note that the two-DVD release includes a theatrical and unrated version, both of which are on Disc One. The difference is eight minutes of footage, the bulk of which entails a lengthier (and worth it) first-dinner scene and another dinner scene in which Dale and Alice spirit away for a bit of not-so-secretive humping.

Presented in 2.35:1 anamorphic widescreen, the picture is strong and vivid. Colors are robust and lines are clear. The only real issues are slight aliasing and a few spots in which flesh tones appear oversaturated.

The Dolby Digital 5.1 mix is sharp and solid, making subtle use of rear speaker action and adequately showcasing Jon Brion's inventive music score. An audio track is also available in French, with optional subtitles in English and French.

The two-disc "unrated" edition includes a lot of material -- much of it is just as funny as what made it into the final cut.

First up on Disc One is a "musical" commentary with Ferrell, Reilly, McKay and, for whatever reason, Los Angeles Clippers point guard Baron Davis. With Jon Brion providing a playful musical accompaniment, the commentary features the participants improvising scads of songs peripherally related to the action onscreen. Often funny and occasionally annoying, this is one commentary that won't shed even an inkling of light on the making of the film.

Five extended and alternate scenes have an aggregate running time of 17 minutes, 32 seconds. Some good stuff is here, including an excised scene in which Dale celebrates getting Hulk hands for Christmas, while Brennan throws a tantrum over receiving a rawhide wallet. Viewers can check out each scene separately or use the "play all" option.

Line-o-Rama is familiar to those who know the DVD versions of Judd Apatow-produced movies. The five-minute, 56-second featurette gathers improvised dialogue left on the cutting-room floor. Highlights include a murderous 7-year-old girl growling that "snitches get stitches" and Ferrell's Brennan hitting on a pregnant woman: "If you need a dula, let me know."

The Making of Step Brothers (22:04) is standard promotional fare, but the cast and crew interviews make it apparent that everyone involved seems to have had a blast. The filmmakers admit they loved forcing Steenburgen's character to drop copious f-bombs.

Also on Disc One is a four-minute, 17-second gag reel, the one-minute, 53-second "Boats 'n Hoes" music video (you'll understand once you see the movie) and previews of other attractions.

Disc Two has a Step Brothers digital copy and a smattering of supplemental material. Six deleted scenes run nine minutes, 35 seconds, while 10 extended and alternate scenes have a total running time of 21 minutes, 27 seconds. The scenes for both sets of extras can be accessed separately or through the "play all" option. There are some funny bits, but a little goes a long way.

Nine segments of job interviews (29:09) that didn't make the final cut are well worth checking out, including some shtick with The Office's Craig Robinson. The material with "the HR lady" is terrific. Dale and Brennan eventually offer sex for a job, with Brennan playing the would-be Lothario: "When was the last time you were worked up by two guys in tuxedos?"

Dale vs. Brennan (6:53) compiles outtakes from a number of face-off scenes between the two. Also worth checking out, if not quite as entertaining, are six therapy scenes with a total running time of 13 minutes, 38 seconds.

Things get sillier. Charlyne Moves In (7:20) is an ersatz behind-the-scenes bit that spins on the conceit that Apatow has given Knocked Up actress Charlyne Yi the OK to live on the Step Brothers set. Ersatz zaniness ensues. Somewhat more successful is L'Amour en Caravanne (12:02). In this fake scenario, the movie shoot is thrown in turmoil when Richard Jenkins romantically pursues Mary Steenburgen and eventually incurs the wrath of Steenburgen's real-life husband, Ted Danson. Look for a great cameo from ... well, just watch it.

It might outwear its welcome just a little, but the offbeat mini-documentary, The Music of Step Brothers(18:14), is an interesting look at how the always-interesting Jon Brion conceived and executed the retro score.

Prestige Worldwide Full Presentation (4:52) is essentially an extended scene from the film. Rounding out the extras is a Red Band trailer and a slew of other previews.

Anchorman and Talladega Nights struck a chord with comedy-starved moviegoers, but Step Brothers, for whatever reason, failed to register at the box office. That seems a bit mystifying, since this Will Ferrell-John C. Reilly celebration of absurdity has plenty of gut-busting belly laughs.