Annoying sibling

My younger sister is so annoying she smokes weed constantly and then bugs me for food at night, try to get me to order Dominos or If I have food in the cabinet she will eat it all because she gets the munchies and if I tell her no she will argue with me, for example she just called me stupid because I apparently left an empty popcorn box in the cabinet because I had the last popcorn well it was MINE anyway, I bought it, I forgot to throw the empty box in the trash she called me stupid because she thought there was food in there and wanted to eat it, I yelled at her because like it's not your food to eat in the first place so why are you mad at me? She turns into a different person when she's high she becomes extremely annoying and argumentative. And yes I am in the process of moving out so please dont suggest I move out if I dont like it because I am.

And believe me I am not selfish with food, I always offer her food when she's sober and she says she doesnt want it so obviously if you don't want it I'm going to eat it, now all of a sudden since you're high you change your mind like no it doesn't work like that.