There are two type of sisters, ones the good friend kind, she'll always seem to be there somehow when you need help and it just seems like a good friendship instead of having a sibling. You and your sister would often ask each other for favours and sometimes pull a couple pranks on each other and can keep a secret, it might seem strange sometimes but at the same time natural.
The other kind is the very annoying type, she is most likely very annoying and would really embarrass you in front of your friends, unintentionally, and intentionally. often quite arrogant and takes every advantage to crush your social life and confidence.
1. my friend carries his sister's stuff to school for her, in return he asks to borrow money from her whenever he has a sudden urge to raid a vending machine for candy.
2. my friend "Ok seriously, every time i come over to your house your sister is screaming, and now she's gonna come to your grad and probably scream because unlike you , she didn't get a date for the dance? That's rough."
Me "yea i know, she's gonna ruin it for me."