Boys will be boys - and so will grown men, apparently. In Adam McKay's relentlessly crude film - his first since Talladega Nights- Will Ferrell and John C Reilly get back in touch with their inner children as two spoiled brats who are still living with their respective parents well into middle age.
Ferrell is Brennan Huff, a 40-year-old whose mum, Nancy (Mary Steenburgen), has given up hope of ejecting him from her life. Reilly is Dale "Call me Dragon" Doback, the equally immature son of Dr Robert Doback (Richard Jenkins). When Nancy and Robert tie the knot, the new siblings are forced to share a bedroom - an arrangement that doesn't suit either one of these arrested adolescents. Lips are pursed. Insults muttered. Threats issued. Blows thrown. These guys hate each other. That is, until Dale gets a load of Bren's super confident little brother, Derek (Adam Scott), married, wealthy, and an instant favourite with Robert. If anyone can unite Bren and Dale, it's the nauseatingly grown up Derek.
On the face of it a formula Dumb and Dumber-style comedy, Step Brothers doesn't aim too high, but its humour is rooted in distinctly painful family ructions. Anyone who has boys in the house (or used to be one) will find plenty to wince at. The peevish put-downs, overweening sense of entitlement and volcanic temper tantrums could all hit uncomfortably close to home if Ferrell and Reilly didn't appreciate the ridiculous side of adolescent angst.
Ferrell and Reilly don't hold anything back. This is a film about childishness, and they rub our faces in it. Adolescence is a dangerous, mixed-up period, when all kinds of unsavoury impulses can surface, and some of the humour cuts close to the bone. It's tempting to see this as a not-so-subtle swipe at the dominant movie-going demographic, the hormonally mixed-up teenage male, just as Talladega Nights satirised those large swathes of the US audiences who make up NASCAR's loyal fan base. But if Ferrell and company like to bite the hand that feeds them, in the end, the mockery is decidedly indulgent; like Adam Sandler, Jerry Lewis and so many other comics before him, Ferrell's childish antics tap an underlying innocence. Think of it as regression therapy.
The laughs come thick and fast as the boys foil various adult strategies to find them gainful employment and sell the house out from under them. It's only when they're compelled to put aside childish things and earn their keep - as all of us must, eventually - that things go a little slack. But this is just a temporary blip. A gloriously improbable happy ending underlines that there is still one line of work in which you never do have to grow up. That would be showbiz and Step Brothers is certainly the proof of it. Where else are you going to see two middle-aged millionaires beating up on a schoolyard full of pre-adolescents?