Emo Girl's Hairline

Alright, listen up, smarty pants. This joke is about an "emo girl," which is a type of person who is typically emotional, dark and sometimes associated with self-harm. You wouldn't know about that, would you? The joke plays on the stereotype that emo people might cut their wrists. So, if an emo girl has red "hair" starting at her wrist, it means she's been cutting herself. You probably thought it was a fashion statement, didn't you?