"'The Hangover' isn't any headache for Warner Bros."

When does a movie studio know they've got a big hit on your hands? When it's a hit even before the movie is released. Such is the case with Warner Bros.' "The Hangover":

Every summer has its surprise hit, and “The Hangover” is starting to look like this season's unexpected breakout.

Even though the bachelor-party-gone-bad comedy doesn't open until June 5, "The Hangover" already is generating such positive reactions that Warner Bros. is developing a sequel, a strong vote of confidence for a movie with no big stars, no comic book tie-in and no obvious franchise traits.

Hey, we've been predicting this on GITs for months now, witness this post, going all the way back to last September, this, and this. The movie has one of the best comedic premises I've seen in a long time:

Directed by "Old School's" Todd Phillips (who parted ways with Cohen during the making of the comedian's "Borat"), "The Hangover" follows a traditional road trip formula.

Four guys (Bradley Cooper, Ed Helms, Justin Bartha and Zach Galifianakis) head to Las Vegas for a night of typical male debauchery, but when they awake in their trashed hotel suite the next morning, the groom (Bartha) has gone missing. To find him, his three friends must retrace their drugged-out steps from the night before, a strange journey that includes a quickie wedding, a naked Asian gangster, an infant found in a closet, a stolen police car and boxer Mike Tyson's pet tiger.

High concept, compressed time frame, frustration comedy (trying to find lost groom), mystery of figuring out what happened the night before, ticking clock, outrageous set pieces -- The Hangover has just about everything you could want in a comedy. And how does the studio know it has a hit on its hands before the film is released?

Starting on May 18, the studio launched an extensive screening program, taking "The Hangover" to 80 cities, showing the film at colleges, military bases and radio station-sponsored promotional screenings. In the last week, the film's cast traveled to eight cities to drum up interest, including Denver, Atlanta, Phoenix, Philadelphia and Miami.

"Everyone who sees the movie loves it," says Sue Kroll, the studio's president of worldwide marketing. "It always ends up with people laughing hysterically and everyone wants to go back and immediately see it again."

Can The Hangover, an R-rated comedy with no big names in the cast, beat out Land of the Lost, a big comedy with special effects and Will Farrell? Both films debut on June 5th.

I'll go out on a limb and say Hangover wins the B.O. crown next weekend.

UPDATE: Nice feature in the NY Times about The Hangover's director Todd Phillips:

“The worst thing about the movie is that it’s about a bachelor party in Vegas,” Mr. Phillips confessed. On the other hand, he said, “we made a bachelor party movie where you never see the bachelor party.”