Even if Will Ferrell didn't keep returning to the same comedic topics (sports, the '70s, those odd fuzzy hairballs that dot his potbelly like ants), it would be easy to feel that he's begun to repeat himself, because he revs so many scenes to the exact same pitch of satirical hysteria. In Step Brothers, though, he does something new. He plays a guy even further down the developmental food chain than usual a 40ish loser who still lives with his mother and he makes this walking punchline a hostile, cussed mess, with four-letter words shock-popping out of his mouth. Ferrell's Brennan Huff is an overgrown 9-year-old who's always in mid-tantrum, and so is John C. Reilly's Dale Doback. The two become bunk-bed stepsiblings when their divorced parents (Mary Steenburgen and Richard Jenkins) marry, and for a while they're mortal enemies, and then (of course) buddies. At which point they really get cretinous.
Step Brothers is a Judd Apatow production (though directed by Ferrell's regular co-conspirator, Adam McKay), and it's the closest that the Apatow factory has come to spitting out a dumb-and-dumber high-concept comedy. Yet it's not just an idiot revel: It's nutty, profane, and caustically heartless. After Dale orders Brennan not to touch his drum set, Brennan doesn't just sit down and play those drums he...well, touches them. (Yes, you see it all.) There are other yeasty bits, from Brennan's vile perfectionist of a biological brother (played with amusing Tom Cruise mannerisms by Adam Scott) leading his family in a hyper-controlled chorus of ''Sweet Child O' Mine'' to the job interviews and therapy sessions that Brennan and Dale turn into kamikaze acts of self-sabotage. Step Brothers is hit-and-miss, but it made me wish that the usual American comedy of how stupid can we get? had this much rage. B