Michelle Trachtenberg on her ''Eurotrip'' bikini scene

Don’t believe that Michelle Trachtenberg has left her kid-sister persona behind? Just check out the former ”Buffy” star’s bikini scene in Feb. 20’s goofy teen raunchfest ”Eurotrip” — there’s no way protective sibling Buffy would have let Dawn show that much skin. Later this year, she’ll further subvert her image in four episodes of HBO’s ”Six Feet Under,” playing a spoiled pop star who employs Keith (Mathew St. Patrick) as a bodyguard. Trachtenberg tells EW.com why she’s glad to have given up vampire-slaying for, of all things, ice-skating — and along the way, she makes us punch her in the stomach.

You look like you’re having a lot of fun in ”Eurotrip.”
Really? We tried so hard to make a somber, very morbid film. [Laughs]

Was this one of those teen movies where the partying was even wilder off screen?
I’m a homebody. My mom was there during production, which wouldn’t have stopped me from partying, but I don’t drink, I don’t do drugs, so I have fun in other ways. And we worked 18-hour days, so honestly all we ever wanted to do when we wrapped was sleep.

How did you feel about doing the big bikini scene?
It was a little stressful. It was the first time that I’ve ever taken off that much clothing — on screen, I mean. But it was such a funny situation. The premise of the scene is that all these gawky, nasty old men have chased away all these hot, beautiful, European sexy women from the nude beach. And I flop up in this big, sloppy sweatshirt and take it off. I was only really disturbed by the 50 naked, disgusting, crusty, grody, naked guys in front of me. It was not normal nakedness.

Who did you base your ”Six Feet Under” pop star on?
It’s a combination of everyone: Britney Spears, Christina Aguilera, Pink, Jessica Simpson, Jennifer Lopez. It was a lot of fun. My character is promoting a new album so she goes on ”The Ellen DeGeneres Show,” which is really cool. She’s also promoting a new movie — with Colin Farrell. She’s an actress, she’s a bitch, she’s a diva in training.

How was the return to TV?
Well, honestly when I left ”Buffy,” I never thought I’d go back to TV, because I’ve done it. I’m not a person to repeat myself creativity-wise. And I found TV to be rather stifling, especially ”Buffy.” Three years as one character — where they’re not changing the character and your abilities aren’t being tested or challenged — gets very repetitive.

If they found a way to change Dawn, or make her grow, would you ever return to the character?
Right now I’m focusing on my movie career. Movies are where I came from. I’m very happy Dawn was in my repertoire. Never say never, but that’s probably not a character I would revisit.

The other thing you’re working on is this Disney movie ”Ice Princess” — tell us about that.
It’s about a girl whose dream is to be an ice skater, and her family doesn’t support that — they’re all about her getting into Harvard. So I’m skating five days a week for, like, two hours a day. I also have ballet every other day to work on the grace and skill.

So you’re in killer shape?
I’m trying [pointing to her stomach]. Take a punch. I’m serious.

[After a gentle punch] Wow. Very admirable.
Yeah, thank you. Rock-hard abs, right?

Um, so can you pass as an ice skater at this point?
Ask me in a couple of months. I’m working very, very hard. My coach said that if I was to continue ice skating after the movie finishes, I could go on to compete. But I will not be quitting acting anytime soon, certainly not for ice skating.