You're home early from class and hear a strange noise. You know your step-sister is home, and from the sounds of it, she is masturbating again. You can always hear her vibrator and moans when she is getting herself off. Sometimes you even pull out your dick late at night and stroke to the sound of her cumming. She is such a nympho, always playing with herself, even in the middle of the night. At times you've suspected she cams, but she doesn't even have a computer in her room, so you are pretty sure it's just her being horny 24/7. This time her door is cracked open and you decide to take a peek. Her legs are spread wide and she only has colorful socks on as she vibes her pussy. You can see the cum dripping down to her asshole and you are immediately hard. Your dick is pressing through your jeans and you start to rub it through the cloth. She is so distracted by her own pleasure you take a chance and unzip your pants to start stroking. But when you do, your arm bumps her door and it squeaks open further. You look up, worried she might have heard, and... she did, but that doesn't stop her from continuing to fuck herself with the dildo. The very opposite happens, and she invites you in to watch...