*Box Office Report: 'Horrible Bosses' Opens to Strong $28.1 Mil As 'Transformers' Becomes Year's No. 1 Movie*

Paramount’s Transformers: Dark of the Moonremained a goliath in its second weekend to become the top pic of 2011 domestically, but there was plenty of business left over for Warner Bros./New Line’s raunchy comedyHorrible Bosses.

The latest R-rated laffer to outpace expectations, Horrible Bosses opened to $28.1 million to place No. 2 behind Dark of the Moon, according to Rentrak.

Dark of the Moon has now earned $261 million at the domestic box office, supplanting Warners’The Hangover Part II ($149.6 million) as the year’s biggest earner.

Overseas, Michael Bay’s 3D tentpole grossed $93 million over the weekend for a massive international cume of $384 million and worldwide total of $645 million—the No. 2 pic of the year behind Disney’s Pirates of the Caribbean: On Stranger Tides, which has now grossed $1.02 billion, the seventh best showing of all time.

Sony and MGM’s new Kevin James family comedy Zookeeper came in No. 3 at the domestic box office, grossing $21 million. The pic cost $80 million to produce, so it will have to do brisk business worldwide to come out ahead.