My Sister Announces Her Presence

I had a dream that I was lying on my bed, messing around when out of nowhere there was one finger doing things that I wanted it to do, just one finger. I tried to get this finger to masturbate for me but it would not. I was flung across the room by this finger, kept trying to get it to masturbate. The finger became a hand. Then, out of nowhere I was grabbed by this person who was hiding underneath my pillow! The person announced there presence and it was my sister. I was completely calm throughout the process. My sister said she wanted to inform me that she was going to figure out my secret soon. I asked her how. By watching a science show.