Naked ambition

"But Vegas is so not my kind of town," she laughs, shaking her head for emphasis. "Fortunately I only filmed here for two weeks. I don't think I could have taken it any longer. When I first got here, Todd Phillips, director of The Hangover and I went to a strip club. I was kind of disillusioned because I'd taken S Factor pole dancing classes and, at the end of the class, everyone would do a dance and be expressing themselves. But if you go to a strip club here, no-one's doing a dance; everyone's just standing there, all the girls are on stage at once and it's all about lap dances, which I didn't realise."

Graham reckons that the S Factor routine - founded by actress Sheila Kelley - got her into great shape even if, ultimately, it proved unnecessary in terms of playing your average Vegas stripper. "It's like get in touch with your sensuality'," she explains, "and one of things you do is find your erotic creature. Anyway, I didn't want to repeat all the hooker-with-a-heart-of-gold cliches with this role, so I tried to personalise it more as a hippy stripper with a New Age/spiritual attitude about sexuality."

Much more difficult - and painful - was when her character had to whip out a bare boob for another reason. "Most definitely the toughest part was breastfeeding a baby," she says. "There were actually six babies on set. Four were great and two were really evil. The mom of the twins that were difficult told me, My baby hates everyone but me'. And then she handed me her baby and it started crying for, like, three hours.

"This breast-feeding business takes a lot of practice," grins the actress who has no children of her own. "I had to start lactating. Because, you know, I'm a method actor ... But seriously, the baby was teething, and it turned out to be the longest day of the shoot. Obviously the baby is not really breast-feeding and so he kept looking around. We had to keep his head facing down towards my boobs. Someone had to stand behind me with a rattler, going, chee, chee, chee'. By the end of the day, it felt like it didn't matter what I was doing, as long as the baby's head was pointing in the right direction."

With her breasts exposed in front of her male colleagues for hours on end, it's just as well Graham is comfortable in her own skin. She didn't always feel this way, however. "My parents were quite strict and religious, so it took a long time before I became comfortable with my sexuality." she smiles. "They even wanted me to be a nun at one stage."

It's hard to know whether she's joking or not. Indeed, Graham hasn't successfully played funny for a whole decade since sharing screen time with Eddie Murphy and Steve Martin in Bowfinger and with Mike Myers in Austin Powers: The Spy Who Shagged Me. But if The Hangover turns out to be the blockbuster hit that the industry predicts, then don't expect her to indulge in any celebratory drinking bouts of her own.

"I'm not a big drinker and just get very sad when I'm hungover," she admits. "That's not to say I haven't had a few wild moments - that shouldn't be exclusively reversed for the guys, should it? A lot of my girlfriends just love to party. One girlfriend had a wild bachelorette party, but she ended up bringing her husband which kind of defeated the point. And she was throwing up into the sink. She had a candy necklace and she was making guys eat the candy off her neck."

Far preferable to getting drunk in Vegas, Graham would much rather relieve her Hangover co-stars of some of their hard-earned salaries. She smiles at the memory of beating them during a crew poker tournament while filming on location here at Caesars Palace. "I came in fourth in the poker tournament, and that's including at least 50 people. They were totally surprised to discover I'm pretty good at poker. I won some money ... " admits the actress, an ardent practitioner of Hinduism who perhaps uses her meditation skills to out-fox the boys at the table. "There's this image out there of me as being a fragile, innocent creature, but I actually enjoy gambling and I love telling dirty jokes. Sex, to me, is funny."

The daughter of a schoolteacher and children's author mother and retired FBI agent father, the Wisconsin-born beauty was raised as a staunch Catholic, mocked at school as "a flat-chested geek". Notwithstanding, she earned a modeling contract fresh out of high school, later trying her hand at drama. After winning a small role in Drugstore Cowboy and more sizeable part in the TV series Twin Peaks, she came to the attention of James Woods, who helped get her cast in sports drama Diggstown, leading to more notable roles in Even Cowgirls Get The Blues and Swingers. But it was her sexy turn as Boogie Nights' Rollergirl that served as Graham's major calling card, earning her lead actress status and the demonstrated affection of a multitude of men including Heath Ledger, Kyle MacLachlan and Ed Burns.

Her devout parents were far from happy, prompting her to say in a recent interview: "Boogie Nights was quite explicit and my parents were horrified. It would be nice if I did have a good relationship with my family and, yes, part of me longs to have a mum and dad who love and accept me for who I am. But if they never do, it's OK."

Early buzz for The Hangover means Graham is already stacking up future projects, including art world satire Boogie Woogie, which premieres in June at the Edinburgh International Film Festival, and indie comedies ExTerminators and Son Of Mourning.

Recently she moved in with the 32-year-old director of the latter, Yaniv Raz. Although she describes the experience as "a big step forward for me, but very exciting too", you've got to wonder if that painful breast-feeding scene in The Hangover would have put her off starting a family.

"I was never really that interested in it," she admits, "but recently I'm like hmmm, that could be fun'. Generally, I like holding babies. They make you happy. They're just such pure joy."

Just not for a 17-hour day under studio lights ...

The Hangover is released on June 12. Boogie Woogie has its world premiere at the Edinburgh International Film Festival on June 26, with a second screening on June 27.