UMD-1010 - My sister and her boyfriend stayed at my place because they couldn't find a hotel, and they're having non-stop sex in my room!

My younger sister and her boyfriend came to the city for work, but couldn't find a hotel room, so they crashed at my place. To my shock, they started having non-stop sex in my room right next to me! I pretended to be asleep, but the sounds were relentless. The next day, I confronted my sister, and she claimed her boyfriend is an absolute beast in bed. When she left for work, I caught him masturbating in my bathroom. I yelled at him, but he apologized while fully aroused, leading to an intense encounter. That night, after my sister passed out from drinking, I ended up getting intimate with him again...