Chris Rock is on a mission to find out what makes 'Good Hair' in his upcoming movie of the same name, and he's dishing to ET about running his fingers through Oprah's hair on her talk show Wednesday!

"It felt good. I hadn't run my fingers through a black woman's hair probably in 20 years, so it was sexy," Rock tells us, adding of Lady O, "She has beautiful hair!

We also caught up with Raven-Symone and Nia Long for the dish on appearing with the funnyman in his new documentary, in theaters Oct. 9.

In the film, Rock explores the sociological phenomenon of what defines 'Good Hair' from the African-American point of view. He travels all across America and even to India to find out why we do what we do to look our best -- or stand out from the crowd. Rock visits beauty salons, barbershops, conventions, scientific laboratories and Indian temples to explore the way hairstyles impact the activities, pocketbooks, sexual relationships and self-esteem of the black community.

Ice-T, Nia Long, Paul Mooney, Raven-Symone, Maya Angelou, Salt-n-Pepa, Eve and Reverend Al Sharpton all share their candid points of view for this raucous expose, prompted by Rock's 5-year old daughter, Lola, who asked him, "Daddy, how come I don't have good hair?"