My dominating sister

My sister loves to dominate me. But after she masters the art of shrinking....

You wake up 5:00 . Your parents are asleep. You go to drink some water. On your way to the kitchen, you hear some noise from your sister's room. You peep inside. Your 18 year old sister is bouncing on her bed. You sneak inside. As you go inside, you hear her moaning. It us then you realize she is masturbating.

what would you do?

         Wake her up