Your sister was sneaking behind the door watching your jerk off your cock to some porn. You noticed her and she comes in wanting to watch too! She is very horny and wants to see the video you were watching. She looks on your history and saw you like brother-sister porn. She wants to watch it with you while she plays with herself. She tells you to get your cock out and stroke it the way she wants you to. Then she shows you her pussy to help you and fingers herself while watching the porn. She likes the porn so much, she goes get a dildo from her room to show her brother how much she likes the idea of getting fucked by her brother. She wants you to stroke your cock until you cum with her! She teases that she should clean up the “mess” for you next time.
