Bradley Cooper's Comedy 'Hangover'

June 6, 2009— -- It's the ultimate cliché: Three guys take their buddy to Vegas for a weekend of debauchery, celebrating the guy's last night as a single man. Chaos ensues, and everybody promises to let what happens in Vegas stay in Vegas.

That is the premise of the comedy "The Hangover" -- at least for the first 10 minutes -- and then it ... switches.

"It's like 'Wedding Crashers' meets 'Memento', or 'Saving Private Ryan'... the comedy," explains Bradley Cooper in an interview for ABC News Now's "Popcorn With Peter Travers."

Two days before his wedding, Doug (Justin Bartha) and his three friends (Bradley Cooper, Ed Helms and Zack Galifianakis) drive to Vegas for an unforgettable night. The groomsmen wake up the next day to find a baby, a tiger and ... no groom. Naturally, they have no recollection of the nights events. The movie kicks in as the trio retrace what happened in a desperate search for the groom.

Cooper, who plays Phil, is best known for the role of Zachary "Sack" Lodge in "The Wedding Crashers."

"Zach was the asshole boyfriend. So I was asked if I'm playing yet another dick. I don't see Phil that way. He's a father, a coach of the little league team who has the chance to break out in Vegas. He's got kids locked to his ankles. All that matters to him is his friends. He's the glue. His bark is bigger than his bite," said Cooper.

In preparation for the movie, Cooper jokes, "We did a lot of research for years. We're in litigation with Warner Bros to be paid retroactively."

Working on set with two improv-trained comedians was hard. "Watching how talented Ed and Zack are in the movie I feel utter hatred," said Cooper with mock seriousness.

Cooper, who prviously shared screen time with Vince Vaughn ("Wedding Crashers") and Jim Carrey ("Yes Man"), found Helms and Galifianakis as talented as Vaughn and Carrey. The competitiveness between the three was nonexistent, according to Cooper, and instead there was total collaboration.

"All three of us are basically unknown. Warner Bros. needs to be known as a comedy studio. So we all had a main goal -- make it work!" he said.

Mike Tyson's cameo in the movie was one of Cooper's favorite scenes, especially when Tyson sang "I Remember."

"He sounded like a robot," Cooper said.