Her best friend is weird???

[hollisterxoxo48241]

Alright my sister has this friend who is 13 and my sister is 12. So i found out that the girl did not like me for some odd reason. So then i found out that she was gonna come over to spend the night on friday so i was really mad at that because she did not like me. When she came over i talked to her about that i like her as a friend and so her and i got over our issues. Then they were doing makeup in the bathroom then i heard that she told my sister that she used to cut herself. Then she was telling us that she drinks achohol and i was really worried for my sister because if she tries to get my sister into drinking then she will get hooked! Then when they were in the bathroom she tried to peirce her nose! then she calls my sister and i dumb asses and i really dont appreciate it. And then i am trying to tell my sister about this girl and how dangerous she could be! What should i tell my sister! because i try to tell her she ignores me and i tried everything and i am not sure what to say