The bachelor party hangover is as much a tradition as the sport that bore it into existence. The throbbing headache, the crust-caked eyes, the soar throat. A sense that you've done something terribly regretful. Now, if only you could remember what that was. You and your buddies have spent the night gambling and drinking in the heart of Las Vegas. You've imbibed in the call girls lingering about the five-dollar buffet. There is a strange rash forming around your thigh area, and there is an abandoned baby in the closet of your hotel room. All of these things can be dealt with later. The day after hangover is to be met with poolside relaxation and bloody maries. But wait! The groom is missing, and he is going to be late for his wedding if you don't find him. This is the dilemma facing three friends in the upcoming summer comedy The Hangover.

Directed by Todd Phillips, this Las Vegas bachelor party gone bad stars an amazing ensemble cast that includes Zack Galifianakis, Bradley Cooper, Ed Helms, Justin Bartha and Heather Graham. Shot on location in the heart of Sin City, The Hangover is a labyrinthine mystery that is set to tip like a stack of dominos. As these three nauseous buddies set off to find their misplaced groom, they must retrace their steps through one hilarious, horrible night of unbelievable highjinks. As Bradley Cooper explains it, "There is a lot of darkness in this thing. I would certainly challenge anyone to rival the night these guys have had. Even in your wildest imagination, you can't top this." Each and every laugh is tied into another, bigger joke. It's a surprise-laden trap of hilarity that will surely pull you to the floor in a heave of hearty guffaws. It's a certified Fort Knox of buffoonery, and it is heading our way on June 5th of this year.

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The Hangover Set Visit #2We recently headed over to Las Vegas to catch these guys in action. Their base of operations for the week just happened to be the magnificent Caesar's Palace casino, and before we could chat with members of the cast, we were forced into their own hung-over mindset. Ever the gracious hosts, Caesar's Palace gave us the full V.I.P. treatment. After a glorious dinner in one of their famed banquet halls, we were taken onto the gaming floor for an exclusive poker tournament. A copious amount of champagne was passed around, expensive Scotch was served, and all had a fun night. Then came the bells and whistles of an early morning alarm clock as we were whisked into the lobby to discover the mysteries of the missing groom. Because of the unexpected twists and turns that {2} takes throughout its intended running time, we were sworn to secrecy about many of its carefully constructed plot points.

Outside the casino, Ed Helms and Zack Galifianakis stood by the valet in character. Disheveled and bloody, they seemed to be waiting for both their ride and Bradley Cooper to arrive. A baby was strapped to Galifianakis' chest. Their exchange of funny dialogue was interrupted by Zack thoughtlessly pulling a pair of Blublocker shades down on the infant's face. As Ed tried to deliver a bout of scripted lines, his concentration was broken by this baby staring at him wistfully. Zack, one of the quickest comedic minds on the planet, played into the child's zombified gaze, matching the infant beat for beat. He replicated the baby's deadlocked stare. It was one of the funniest things I have ever seen on a movie set. Ed couldn't contain himself. He started laughing, and it became contagious amongst the crew gathered around the valet. This seemed to upset their director, Todd Phillips.

With the blame mostly on Ed, Helms wanted to look at the situation in a different light, "Zach is a compulsive liar. You can't believe anything he says." Ed didn't see the baby as the root of the problem, "Working with the baby has been a delightful experience. Babies are just little kernels of joy. They are sort of like little joy pillows. Little puffy, cuddly balls of joy. It brightens your day just to be around a baby. But they're so unpredictable that it's also a colossal pain in the ass. I like having babies around. I love 'em. I just like babies. I like being happy. And they make me happy."

It's a comedy, so you can't really blame people for laughing. It seems to happen on this set all the time. This was not a rare exception, says Ed, "Oh my god. You couldn't see what the baby was doing. Neither could Todd. That's the thing. Zach has these Blublocker glasses. They're actually the glasses that his character wears. Do you know what Blublockers are? If you've ever looked through them, it's like the world's a happier place. They're really awesome and there's zero glare. It's just sort of like everything's brighter and happier. When he put them on the baby, the baby would go wide-eyed. On the first take, he froze and was staring right into my eyes. Of course Zach is mashing the glasses against his face, and the baby knows he's squishing them around. I just couldn't deal with it. It was the funniest thing I've ever seen. That baby. It has these white, zombie-like eyes. The craziest, most-intense eyes I've ever seen. It just wrecked me."

The Hangover Set Visit #4This is not the first time an actor has cracked during a scene on this raucous set. Justin Bartha admits that he might be the worst offender, Yes, I laugh through pretty much every take. These guys are so funny. Everything that Zack does makes me laugh. I ruin a lot of takes. Bartha has even gone out of his way to make it work for the film, I try to work a laugh into the scene so that it seems natural. I don't want it to seem weird that this guy is laughing. Funny things are being said. It makes sense that this guy would be laughing at some of this stuff. Ed claims he might be worse at keeping a straight face than Justin, It's not a badge of honor to make me crack up because I laugh very easily. I laugh too much. It keeps it fun, but the problem is that you sort of get the giggles and then there's Zack. For some reason, he and I just have this feedback loop. It starts to happen and it's happened a few times where we just can't stop laughing. I mean, he genuinely cracks me up. Zack just makes me laugh walking around, talking. And then his character is really funny. It's such a perfect character for him. One of the best things about his character is that he doesn't really get anything. He never catches onto it. Like a joke. So he always has a very innocent response to something. There's this one exchange where I say something really sarcastic to him and he's just delightfully oblivious and it just cracks me up.

Of course, this is to be expected on a set where improvisation is a key element to the madness we will see on screen come June. Zach explains, "Todd Philips lets you do your thing. Any actor can go vomit out lines. He lets you make stuff up. We do it the way it is in the script, then we get to play around. There is a lot of freedom, which is really gracious on his part. You have to do the improvisation within the realm of the character. You can't do it just for the sake of the joke. I have done it a couple of times where I realized that my character would never say that. So I will give t to one of the other characters. And vice versa. If it doesn't feel right, I won't do it. Sometimes Todd will come up to me and say, 'Alan wouldn't be doing this.' And I have to agree. It's something that I have to keep in check. You can't just do it for the sake of the joke. It definitely has to be right for your character."

The Hangover Set Visit #5A lot of great material is coming from the interaction between the actors themselves. There is a great synergy on set. Bradley Cooper attributes the film's high energy level to his co-workers, These guys are hilarious. I am very lucky to have this job. I didn't realize how good of an actor Zack was until I saw him in this. And Ed? He is phenomenal. He kills it. I am just trying to keep up with them and keep my head above water. It's a challenge to run with these guys. I am running with a fast pack in this movie. I am constantly trying to keep up. Bartha, who plays the missing groom in the film, hasn't even brothered to keep up, as he is the intended straight man of the bunch, For me, I just try to set it up so they can hit it out of the park. They are the improvising guys. That's not my character, Doug. I am letting everyone else do that this time out. And it's kind of a relief. It really is. I am just sitting back and watching these guys work. They are so brilliant at coming up with stuff. I always feel like I am the one that has to do that kind of thing. It's nice to take a backseat.

Director Todd Phillips says it's the only way he can work, "I did it with Road Trip and Old School. And Starsky. It's been this way with everyone I've worked with. They all like to improvise. I think any comedy director that is good at it allows for that. It is up to the director and his performers to find out if the improvising fits the character. That happens before the camera even starts rolling. Ideally, you have smart guys. And 90% of that time, the improv they are doing fits the character. What I generally like to do is shoot the scene as is. And then we fuck around and find other stuff." With the studio looking to release an R rated comedy, Todd feels more comfortable letting the actors be who they are on screen, "It enables me to do more of the stuff I want to do as a director. I get to cater to my line of taste as far as comedy goes. When you have a guy like Zach, and you are doing a PG-13 comedy, it would be hard to let him go. He has a certain inability to censor himself, and that sometimes veers into R rated territory."

Zach blames himself for the film being ripe with explicit humor, "They wanted this to be G until I jerked the baby off. It was going to be a Pixar film. I think being R, and being dirty, especially with the language, has run its course. This film has that in it. But it also has a lot more. A lot of that Apatow cursing just to curse has run its course. I maybe shouldn't be saying that. This has a lot of elements to it. It doesn't exist just for the sake of being R rated. It's more clever than that. There are some very smart parts." Wait. Did he just say he jerked off a baby? "There is a baby doll. It is a stand-in. It looks like a real baby. I was acting like the baby was masturbating himself. And Todd goes, 'Oh, I have to put that in the movie.' So Todd had to ask the parents, 'Do you mind if a grown man is acting like he is jerking off your baby?'" What did the parents of this very young actor think about that? "I wasn't there for that diuscussion. I would have been too embarrassed to face them. There is no way I could have watched that. I'll just say that people pimp their babies out."

The Hangover Set Visit #6Shooting in Las Vegas is rough, it seems. And the boys behind The Hangover have found it tough to live down the title of their own film. Prior to our arrival, Zach had spent the night partying it up and Nick Cannon's birthday party with Mariah Carrey, "I went out last night. I shouldn't have done it. I got in at 4 am. We went to a nightclub. Today I am paying for it, for sure. I am aching. Its just research." A rumor had circulated that Zach even went swimming in the famous Caesar's Palace fountain, "Yes. I did go swimming in the Caesar's Palace fountain. It was for the movie. I wasn't out there just doing that on my own. It was tempting to get back in that thing on my own, though. I did a few laps around it the first time. I haven't gotten into a fountain for a couple of weeks now." The pros of shooting in Vegas simply outweigh the cons, "The pros are that you can get prostitutes at the food court. The pros are this energy that is just constant. It's awesome to shoot in the casinos, because they pump so much oxygen in there. I think that is what keeps me going, because I haven't really slept. You go off the energy of the casino life here. It's easy not to sleep. I can't get any sleep here."

According to the other actors, Zach is pretty much by himself when it comes to staying out late, drinking and acquiring the method actor's hangover. Cooper tells us, "I just work. We've been working this entire time. Oh, there has been a little bit of gambling. But like I said, I could get in trouble in this town. I try to stay away from those sorts of things." Justin, on the other hand, has more downtime then the rest of the cast, as he is absent from the middle section of the film. His gambling addiction has gotten out of hand, "I am not a big partier. I went out one night. And the pictures wound up everywhere. I like to gamble a lot. So I have spent all of my per diems and most of my paycheck. I play poker. And blackjack. And craps. The slots. Baccarat. Roulette. I will even gamble in the streets. Dice. Any kind of thing. I am about even so far. Before we leave, at the end of the week, I will have to make some huge bets. Just so I can say I won big or lost big. You can't walk around saying you broke even."

The Hangover Set Visit #7This being Las Vegas, the live entertainment capital of the world, will there be any cameos in the film? Well, we know Mike Tyson makes an appearance, but the cast is keeping a tight lip on who else might drop in for a visit. One Vegas luminary that won't be turning up on screen? To Zack's disappointment, Danny Gans. Danny Gans is not in this. I think Carrot Top is in this, but not poor Danny Gans. There is a guy named Tom Stevens that is a poor man's Danny Gans. I can't wait to go see him. I want too so badly. Todd wants you to know that there are definitely some great moments in store for the audience, Yeah, we have a couple of surprises. I would like to keep them as a surprise. But we do have a couple of really good ones. And I don't think you will be disappointed.

Shooting a comedy in Las Vegas has been an odd experience. Bradley parted our conversation explaining the cruel nature of the shoot, "You finish work, and you go home. And it's tranquil. Here, you finish work and you come back to this casino. And it's as if nothing has changed. And no one cares, either. It becomes so inconsequential, the gambling and this town. That is the pulse of this city. Sometimes you go into a town to shoot, and it transformers. But here, they don't even give a shit. We are the background. We shot in a casino the other night, and we definitely were the background." Phillips agrees, "This is a dark place. We have already lost a couple of crew members to Vegas. It is a hard thing to balance that and shooting a movie. It is exhausting."

The Hangover is sure to be one of the surprise comedy hits of the summer. You can join in on the fun when Todd Phillips latest hits theater screens on June 5th, 2009. Just don't plan your bachelor party around it!