Sneaking In

I had a friend who I regularly had sex with, we were both about 18 at the time. She was more into the BDSM side of things than I was but I enjoyed the spanking side of things and stuff, nothing too out there. One day, in bed after we'd fucked we started getting really into what we liked and didn't like, she ended up telling me that she really wanted to be fucked out of nowhere and have it be a big surprise, especially when there's somebody else in the house. I could barely resist her those days so we came to an agreement that I would turn up to her house one day when I knew she was there and use a hidden key to sneak in and fuck her. I don't think I've ever felt so nervous and ecstatic in my life, one day, around 7pm when her Mom was home, I snuck in a backdoor key and somehow mananged to sneak upstairs where she was in her room. I could feel my heart racing yet my cock getting really hard. I waited for her to face away from her door and I opened it quietly and walked over to her and gently placed a hand over her mouth and pulled up the tight skirt she was wearing and we fell on the bed. I then had the most amazing sex I've ever had, all the while tsaying very, very silent.