Gems like Elf and the genuinely affecting Stranger Than Fiction have expanded on his clueless man-child schtick, but Ferrell's infantilism grows tired for those of us who've had our fill of dick jokes and child-men on the loose.

Anyone who’s seen a TV ad or trailer for the movie will arrive at the theater knowing the bulk of what will transpire: Brennan Huff (Ferrell) and Dale Doback (Reilly) are two adults suffering from serious cases of arrested adolescence. Both still live at home, Brennan with his mom, Nancy (Mary Steenburgen), and Dale with his dad, Robert (Richard Jenkins).

A love-at-first-sight meeting between Nancy and Robert justifies a quick wedding that brings the four together as a family under the same roof. This forces the two adult children to share a room, and they deal with it about as well as real 12-year-olds would; a nasty step-sibling rivalry where sacred toys must not be touched, dinner table stare-downs are law, and vicious insults and threats are all in a day's work.