Last year my BF (28 M) and I (23 F) were asked to house sit for his sister who was going out of town.

My BF had always brought up sexual fantasies about his sister and other family members. On previous occasions, I would sometimes make him call out her name as he fucked me, which would always lead to the biggest orgasms.

Back to housesitting.... I knew that the thought of sleeping in his sisters bed was already making him super horny. When he got out of the shower on the first night, I was naked on her bed wearing one of her lace thongs. His cock was immediately huge and red. He came to kiss me on the bed, but I rejected it.

Instead, I turned him around so he was facing the headboard. I had never fucked him in the ass, but this was going to be my opportunity.

I kissed his back and made my way down to his butthole. He was hesitant at first, but he always listens when I tell him to shut up. From behind, I put some lube on his cock and started rubbing between his asshole and his dick. He was moaning like crazy. I then bent his head down so his ass was in the air. I licked all around his anus and put his balls in my mouth, all while stroking his cock. He was practically screaming at this point as I kept asking if his sister would approve.

I then gently put my pointer finger right in his asshole. It slid it so nicely. I could feel his cock get harder and harder as he was going to explode.

I then bent his head down so his ass was in the air. I licked all around his anus and put his balls in my mouth, all while stroking his cock. He was practically screaming at this point as I kept asking if his sister would approve.

I then took off his sisters thong I was wearing and put it right under him. As I was stroking his cock and fingering his ass, I told him I want him to cum all over his sisters thong. I told him I want her to unknowingly walk around in a thong her brother had cum in.

He busted so much cum that it covered the thong and went all over his pillow and sheets. It was a huge mess. It was also just the beginning of our sex stories in his family members houses.