By Janet Mock
August 27, 2009 02:05 PM
Ron Asadorian-Eddie Mejia/Splash News Online; Landov

Mariah Carey may have shed her glamorous look for the gritty drama Precious, but it didn’t stop the singer from talking about the fabulous life with costar Gabourey Sidibe.

“Mariah and I would sit and talk about fashion and perfume and jewelry,” the 20-something acting newbie – who plays the title role in the film – told

“It was like sitting in junior high and talking to your bestie,” Sidibe added of bonding on-set with Carey. “She hated her wardrobe! We all hated our wardrobe!”

In Precious, which tells the story of a young girl growing up amid terrible domestic abuse in Harlem, New York, Carey transformed herself into a dowdy social worker.

“No one has said, ‘Girl I can’t believe you are there with those dark circles under your eyes and wearing a wig and looking nasty,'” Carey told PEOPLE in May. “No one went that far.”

But Sidibe isn’t looking to keep Carey as her only star bestie: she has her eyes set on Oprah. “I have plans to imprint myself in her life,” she joked. “She’s about to be my fairy godmother. She has no idea!”

The heartbreaking drama, which won both the Grand Jury Award and the Special Jury Prize at Sundance, comes out on Nov. 6.