Hollywood star Lindsay Lohan has promised fans her first movie sex scene won't be too gratuitous - she keeps her bra on. Lohan admits her mother Dina was horrified when she realised the 21-year-old would be simulating intercourse in the murder thriller I Know Who Killed Me. She says, "Did I go naked for it? No, I had a bra on. "I told my mom about it and she screamed. "I was actually so nervous but then I was fine. It's weird."