Sister troubles?

My sister hates me. Plain and simple. If she goes over to somebody else's house, as soon as we get in the car, she starts to annoy me ON PURPOSE and call me hateful names and make fun of me. She always gets the good stuff where I'm stuck with nothing, and when I try to get the good stuff for myself, she says, "Oh..well..I was gonna get that, but you can have it, I guess.." you know, the whole guilt trip thing. Help??