She gave real oral sex to her douchebag boyfriend/The Director of one of her movies for a scene they did in The Brown Bunny I think it was called. When Ebert gave it a really bad review Lover Boy went apeshit and called Ebert a fat piece of shit or something. Ebert then had the greatest put down ever: "I may be fat. But one day I will be skinny. Where as The Brown Bunny will always be a movie you wrote and directed."
Meh overall btw.
You're thinking of ChloŽ Sevigny.