Pretend I haven't seen it

Over the weekend, since everyone I knew was out of town, I realized exactly how annoying my sister is. I learned that I should never, ever tell my sister that I've already seen the movie we're about to watch. I've learned that I should never, ever watch a scary movie with her. I pretty much learned not to watch movies with her. From the getgo she wants to know "Why is he doing that?" "Where are they going?""What's happening?"(as she's turned completely away from the TV and she's got her fingers in her ears as to avoid knowing what's happening in the scary movies). Even in movies that I've flat out told her I have not yet seen, she still asks me questions. Through the entire movie! She wants to know what happens at the end of the movie when it's just beginning. She'll say "He dies doesn't he?" "That's the killer huh?" or something to that effect. Then she'll get up and go in the other room for extended periods of time and then comes back and wants me to explain what happened. So...if by mistake I tell her that I've have seen it, I just say "Pretend I haven't seen it." because she'll ask me questions and then get pissed when I don't tell her. No wonder I don't hang out with her and watch movies.