I think my friend has a personality disorder?!

This is either a Narcissistic Personality Disorder or a Borderline Personality Disorder. You can Google both disorders and read about their symptoms and see which one best fits her.

In order to develop a personality disorder, someone has to receive abuse and/or neglect as a child. Due to these conditions, they learn inappropriate coping skills, behaviors, way of relating to people and ways of functioning. We cure these disorders with years and years of psycho therapy to teach the patient new life skills, ways of coping and the correct ways to relate to other people. These disorders are a serious lifetime problem and she won't be able to make good, lasting relationships in her life without correcting her problem.
No, its not you, it's her and you can stop her bullying by reporting her. There is nothing so frightening to someone with these disorders as getting into trouble for their obviously wrong behaviors....just make sure you can back up everything you report with a recording or a witness because she will turn this around and try to blame you and excuse herself.

You cannot answer people on Yahoo answers if they don't allow contact like myself. But if you have another question, please post again and I may catch it and answer it.

I did psychiatric intake work at a good hospital for many years.

Does this sound like her?:

1. Has a grandiose sense of self-importance (e.g., exaggerates achievements and talents, expects to be recognized as superior without commensurate achievements)
2. Is preoccupied with fantasies of unlimited success, power, brilliance, beauty, or ideal love
3. Believes that he or she is "special" and unique and can only be understood by, or should associate with, other special or high-status people (or institutions)
4. Requires excessive admiration
5. Has a sense of entitlement, i.e., unreasonable expectations of especially favorable treatment or automatic compliance with his or her expectations
6. Is interpersonally exploitative, i.e., takes advantage of others to achieve his or her own ends
7. Lacks empathy: is unwilling to recognize or identify with the feelings and needs of others
8. Is often envious of others or believes others are envious of him or her
9. Shows arrogant, haughty behaviors or attitudes
10. Often mild to moderate paranoia, that others are out to do him in.
11. Predominant "name dropper" boasting or suggestion association with people or affiliations of importance.

If your still in school or a place where there's alot of people that's just how people are and she might be putting her past of being an outcast who was made fun.so she makes fun of her self to feel better to fit in. " The more tragic a life is for a clown the funnier he becomes" I did it I laughed at my self and dised myself a number of times so I could feel like I fit in and so nobody would make fun of me, she might have issues but she is doing it so nobody else takes advantage of her and make fun of her

This is called OCD.
and do not call her a friend, you don;t want to be around these people, I've had the same thing.
Stay away, it will make you miserable.