In a Rolling Stone interview, Christina Ricci talks about self-mutilation and pain when a teenager:

She stretches; her sleeves ride up; there are raised round scars on her forearms, burns on the back of one hand. She later explains where each mark came from: how she heated a lighter, held it against her hand, a stunt to impress some boys when she was angry about "not looking very good."

The forearm scratches come from soda tops and fingernails: "It's like having a drink," Ricci says, "but it's quicker. You know how your brain shuts down from pain? The pain would be so bad, it would force my body to slow down, and I wouldn't be as anxious. It made me calm."