When you hear that Adam McKay, Will Ferrell, and John C. Reilly had so much fun making Talladega Nights that they decided to throw another movie together just for fun, you have pretty clear knowledge -- or at least hope -- of what you're going to get. There will be comedic male nudity (and really, what male nudity isn't?), there will be guys self-seriously comparing themselves to ninja unicorns, and God willing, someone will get buried alive. Step Brothers delivers on all this, as well as on the infamous R rating (Ferrell himself reveals his own full-frontal crown jewels within the first half-hour, though, of course, it's possible that they're prosthetics), a notorious first for McKay, an Upright Citizens Brigade alum and longtime Ferrell collaborator. There are big, stupid belly laughs at big, stupid gross-out jokes from opening titles to closing credits, and despite the distinct feeling that none of the comedic triumvirate were waiting around for a script with a truly innovative story, they all make use of the open-ended premise. (Two 40-year-old men with curly hair act like nine-year-olds, except with more dick jokes. The end.) There's tons of room for awesomely offensive and over-the-top improvisations, and at no point does it feel like anybody is playing it safe or pushing the boundaries -- everybody is just going with their first, most hilarious impulses. The unmistakable chemistry between Ferrell and Reilly was enough to inspire the production of this movie in the first place, and it's more than enough to propel it. For all his indie cred and accolades, Reilly is right at home playing a middle-aged man-child who insists on being called "Dragon" and wants you to fight him with a bo staff. Likewise, this is Ferrell's bread and butter, though the alchemy that happens when he shares the screen with Reilly brings out something new -- something you can't quite, in fairness, call "refined," but is still, nonetheless more impressively focused than his usual schtick. And it's not just the leading men who make Step Brothers such a good time; Kathryn Hahn (the office lady in Anchorman who tips Christina Applegate off about the teleprompter) makes an awesomely over-the-top appearance as the WASP-y, sexually frustrated wife of Ferrell's little brother -- a douchebag Dane Cook bro played just as expertly (if also terrifyingly) by a Heineken- and Creatine-buzzed Adam Scott. Obligatory cameos are made by regulars of the Daily Show and Apatow crowds, but those moments are pure icing. The delicious molten chocolate center is just watching Ferrell and Reilly act like idiotic geniuses.