Elf Sternberg

Wild hair and dirty shirt are part of some kinds of crazy. She sounds like someone whose social norms and inhibitions have eroded due to any number of reasons. Brain injury, abuse, drug abuse, progressive mental illness all come to mind.
Or maybe the social norms and inhibitions weren't there in the first place for her - some folks have a great deal of difficulty understanding social norms and understanding why they matter. Some of the kids I work with will probably grow up like that. In my own family there's a history of cyclical depression and bipolar disorder, with at least one member of my family having serious difficulty with certain aspects of social interactions and with certain kinds of self-care. The person Elf described almost sounds like this member of my family on a really bad day.

Or maybe she's just lazy and selfish.
I hope when I'm having a bad bipolar day, I'm not next to you in line. Though I promise I'll do my best to keep my crazy to myself.