

The raised eyebrows started pretty much the moment the trailer hit the Web.

"The Hangover Part II," Todd Phillips' follow-up to his 2009 smash, wasn't just bringing back the same characters and actors as the R-rated original. It was returning the same structure and plot devices -- good friends lose track of someone from their group during a bachelor-party bender and must then piece together what happened. The pre-release line on "The Hangover" was "It's original and crazy." The pre-release line on "The Hangover 2" was: "Isn't this the same movie I saw two years ago?"



Critics didn't help as the reviews began to roll out: the Rotten Tomatoes score for the new Bradley Cooper-led ensemble comedy was a dismal 36%. (The original notched a respectable 79%.)



And yet when the movie opened this weekend, audiences devoured it. "The Hangover Part II" took in more than $86 million in the Friday-Sunday period alone, the biggest total for any 2-D offering this year. The film's five-day weekend haul of $137 million helped this Memorial Day weekend set an all-time record, downright stunning in a year when most weekends have seen drops over previous years.

Even more remarkable is that the comedy is on pace in the U.S. to outgross the original -- no mean feat when you consider the first film tallied $277 million to become the most lucrative R-rated comedy of all time. How did it manage all of this?



Comedy sequels are a strange bunch. Many of them don't get made in the first place (witness studios pulling the plug this year on new "Anchorman" and "Zoolander" films). And those that do often disappoint, both at the box office and with fans. Some are outright dogs -- hi, "Sex and the City 2." Others just peter out quietly. You can extend movies in genres such as science-fiction and horror with relative ease. Try to continue the funny and you frequently end up with yawns.



But if you start ticking off the successes and failures, a pattern begins to emerge: Those that succeed tend to hew very closely to their originals. Once they start departing from what got them laughs and dollars in the first place, their chances of success dip.



There are exceptions, of course. But the pattern holds up surprisingly often, as a quick look at the comedy sequels that tried to mix up the formula demonstrate. "Evan Almighty," the follow-up to Jim Carrey's God comedy "Bruce Almighty," made some notable switches when it came out in 2007. Gone was the lead actor, for instance, as was the premise of the divine in everyday life, replaced by politics and a biblical flood. The movie's global box office plummeted by $300 million from the original.



Then there was "Night at the Museum: Battle of the Smithsonian," which changed up much of its supporting cast and tweaked its concept from a science-based comedy to a historical one. It, too, grossed considerably less than its predecessor.



When filmmakers make even more radical changes, things can really get gummed up. A few years ago, Sacha Baron Cohen decided to take a different one of his clueless foreigner characters from cable television instead of continuing the antics of "Borat." The resulting film, "Bruno," took in less than half of the "Borat" total. Studio comedies are comfort food, and we generally don't want the same dishes made with new ingredients.



In contrast, the few comedy sequels that have worked in recent years rehashed the same shtick. "Austin Powers: The Spy Who Shagged Me," for instance, came back with an almost identical set of gags in 1999 and vastly outdid its first installment. Ditto for "Meet the Fockers" and "American Pie 2." Few would say filmmakers were doing anything dramatically different with these sequels. But the lack of chance-taking, paradoxically, paid off.



Phillips and the "Hangover" screenwriters have caught some heat for playing it safe. After a major blockbuster, Phillips had the clout to do pretty much whatever he liked with his characters in "The Hangover Part II." Why, after making such a bold movie, would he just try to do the same thing with a new backdrop? But while Phillips may have made a creatively questionable decision, he made a savvy financial move. Comedy sequels have a better shot at the dollars if they stick to what got them there.



If that sounds a little depressing, there is some solace in another fact. Once a movie generates this much money in a second installment, there's usually a third edition not far behind. But audiences tend to punish those movies no matter how safely they play it.

So there might yet be some karmic justice for those not enamored of "The Hangover Part II" -- in 2013.



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The Hangover Part II trailer takes us back to an earlier day



-- Steven Zeitchik

twitter.com/ZeitchikLAT

Photo: "The Hangover Part II." Credit: Warner Bros.