Will Arnett, Lake Bell, Zachary Quinto, Danny Masterson, Shoshanna Lonstein Gruss and Paula Abdul joined Cooper and Bartha for the party and screening of their film, which, as its title suggests, is about the brutal morning after a booze-laden bachelor party blow out in Las Vegas.

The cast had their own experiences of intemperance to draw from. "I never threw up and I never blacked out, but some would argue that I wasn't in any state of handling my liquor," said Cooper, who said he doesn't drink anymore. "I guess when you lose your motor skills you're not exactly 'handling it.'"

Bartha, for his part, seemed quite clear about his limits. "One too many tequila shots and I will throw up everywhere," said the actor. "So watch out." (Perhaps that's why Bartha's girlfriend Ashley Olsen was nowhere in sight?)

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