My friends treat my sister like crap........?

Ok my fraternal twin sister is a butch ,but of course I still love her.When ever me and my friends hang out and she comes around they just look at her like "eeewww..." and i have told them to be nice to her,because i love her and she doesnt bother me and they are still just as rude.They dont want her talking to me or anything one my friends was at our house and i had just changed out of my school clothes and my sister comes up and gave me a slight hug and after she left my friend was all you need to put on some new clothes cause those are dirty (they werent).They say that just because my sister is gay that means she has a crush on me.They say "I bet she has a crush on you" and crap like that! They accuse her of liking them and my sister told them "just cause im gay.dont mean i like you".They said "whatever" and rolled their eyes im sick of them.Her friends are always nice to me! The other day it was "ooohh shannah i saw your sister kissin her gf".How do either get rid of my friends or convince them to be nice?