Sex and the City
. "I had no idea you saw his butt in half of it," says Dawson, who has dated the actor, 33, for nearly a year. "My mom is like, 'Your boyfriend has a nice butt.' I said, 'That's it. I'm turning this thing off.' "
Such prudish moments are very rare for the adventurous Dawson, 25. "I am a pretty fearless person," she says. She proves it as an Uzi-toting prostitute in the new film Sin City
, in which she sports a mohawk and a barely there leather-and-fishnet ensemble. "She was like, 'Hell yeah, I'll wear it,' " says director Robert Rodriguez. "You have to have a lot of confidence to carry that off." Part Puerto Rican, African-American, Irish, Cuban and Native American, Dawson was discovered while sitting on her New York City stoop at 15 and made her debut in 1995's racy Kids
. She has since shined in 1998's He Got Game
and 2002's Men in Black II
(next up: a film version of the hit musical Rent
) and even sees the bright side of going topless in last year's flop Alexander
: "In 80 years I will be able to look at that and say, 'I had a pretty nice rack back then.' "
Rosario Dawson just wanted to show off boyfriend Jason Lewis to her mom, Isabel. So she popped in a DVD of Lewis as Smith—Kim Cattrall's impossibly gorgeous younger beau—in