Jason Statham's Crank is well known for its scandalous scenes, especially the Chinatown scene with Amy Smart, who used a stunt double for parts that required her character to show skin in front of all the background actors.
While the editor did a good job making it look like Amy Smart was having fun with Jason, it was actually Laura Grady's body that was visible:
Amy wasn't comfortable stripping for the scene, which was filmed in front of multiple background actors (and let's not forget the dozens of crew members), so Laura stepped in and had a blast with Jason. She told Vulture:
My funniest moment on set was Crank. Jason Statham made me feel so comfortable. I can't remember exactly what he said, but I remember telling my husband later—something so charming, like, 'Don't worry, I've got this, honey.' He didn't make me feel stupid or naked. And I had to be completely topless, and there was this crazy scene outside with all these background actors. But I was like, 'This is not a bad day. I'm getting naked for Jason Statham. I'll be fine today.' I remember getting the call for Crank 2; Amy Smart asked me, and I thought it was really cute. But I was pregnant and couldn't do it, and I was so upset. But you can't be a pregnant body-double. It's a responsibility.