Chris Rock is violating the first rule of Sundance celebrity: It's the second Friday of the festival, and he's still here.

Writer-narrator-interviewer Rock and producer Nelson George (pictured) were on hand Friday for the last screening of "Good Hair," a documentary about African-American women's hair. And if you don't think that's a ripe subject for a documentary, you will by the movie's end - and you get a solid dose of Rock's comedy along the way.

Rock has been interested in the topic of black women and their hair - and how they spend thousands of dollars to make it straighter and more like white women's hair - for about 15 years. It was when one of his little daughters asked, "Daddy, why don't I have good hair?" that Rock decided finally to tackle the topic.

"If I had done it 15 years ago, I would have been much more judgmental," Rock said in a post-screening Q&A. "Now I just chalk it up to style."

Rock cajoled a lot of his friends and fellow performers - including Nia Long, Tracie Thoms, Eve, Meagan Good and Raven-Symone - to be interviewed. For an interview with rapper/actor Ice-T, a trade was involved; Rock agreed to appear in a documentary Ice-T is producing.

"When you're making a movie like this, and you're not paying anybody, you kind of take what you can get," Rock said.