With reporting by Josh Horowitz

Short hair, don't care? That certainly wasn't Olivia Cooke's attitude when she signed on to play teen cancer patient Rachel in "Me and Earl and the Dying Girl," but the character looking authentic was important to her.

In an interview with MTV News ahead of the release of the new movie, Cooke and co-star Thomas Mann told MTV News about Cooke's decision to shave her head for the role -- on camera.

"It was never said, like, you have to shave your head," Cooke said, but "bald caps look awful."

Mann described the steps of shaving her head as pigtails to mohawk to full shave to, as Cooke called it, "this weird bubble of, like, scream-cry."

"I've never produced that sound," she said.

Find out more about Mann shaving Cooke's head in the video below.

"Me and Earl and the Dying Girl" is in theaters today.