Sarah Michelle Gellar and fiancé Freddie Prinze Jr. already share a home — do the lovebirds really want to be together at work too? Surely no couple is that cozy. "It depends on the project," admits Gellar, who plays Daphne to his Fred in Scooby-Doo (opening tomorrow).

"There was no concern [Scooby] was ever going to cross over into our real life," she laughs. "It wasn't heavy and dramatic, like we're taking it home. Freddie and I were obviously quite familiar with each other, and I've known Matthew Lillard" — who plays Shaggy — "for eight years. So it was nice not having to say, 'Hi, I'm Sarah' on the first day."

That freed up Gellar to deal with Daphne's "physicality" issues. "I studied the way Daphne always posed [in the cartoon]," she says. "Her body's constantly at an angle. I'm telling you, Daphne must have some chiropractor because, seriously, it hurt!

"I would be standing in my Buffy trailer running these Scooby lines with James Marsters, who plays Spike," Gellar recalls. "At the same time, I'd try to adjust my body and make [the posing] natural. Daphne poses and it just doesn't stop!"

Gracious as she is, there's one Daphne-related query you don't want to ask Gellar: "What would I do for a Scooby snack?" she sasses. "That's dog food. Let me tell you how nasty that is. I won't do anything for those! On the set, they were this nasty concoction that looked good on camera — but by the third or fourth take, we're like, 'Someone get a spit bucket, please!' They're not going to be able to market those things with the nasty things I've said!