[m]y very curious step-sister and her [f]riend

Let me preface this story with a little background. This happened 3 years ago. I was 20 and my step-sister and her friend was 18. My mom married her dad when we were 14 and 12, respectively. She always has friends over the house and I've known all of her friends for a few years.

It was a Friday or Saturday night because she was allowed to have a friend sleep over the house. I knew this girl, but not as well as the rest of her friends. Her name is Amanda. Amanda and Sam (my step-sister) were up really late that night doing well… whatever girls do at sleepovers. Our rooms are connected by a bathroom with sliding doors on both ends. Picture my room being on the far left, then a bathroom in the middle, then her room on the far right. Our parents slept all the way on the other side of the house. I was really tired that night. I think I was up late the night before playing a new video game, so I decided I should fall asleep at a decent time. It was around 12:30 AM I was awoken to the sound of obnoxious girly laughter. The kind that pierces your ears because it's on a whole other frequency level. I was about to leave the comfort of my bed to go yell at them to keep it down, but just as I was about to get up I heard what they were talking about…