My SIL to be was staying with us one weekend, her and her BF (Fiance's brother) we're going to a concert. He left earlier in the afternoon and she was stopping at the house after work to change before she went to the venue. I've always found her extremely attractive.. 5'7", dirty blonde, incredible ass, and amazing tits. I've gotten to see her in a bathing suit almost more times than I've seen her in street clothes. I've never been into the idea of panties, but after she left, I went upstairs to look for her dirty clothes. She had left them neatly piled on the bed, and in the middle of that pile was her used cotton thong. I found myself so incredibly turned on by the thought, I couldn't help myself. I went into my bedroom and wrapped that thong around my cock, stroking myself to pics of her from our recent family vacation. It was one of the most intense orgasms of my life. Took everything in me not to completely soak that thong with my cum. When I was done, I neatly tucked them back into her pile, wishing by some chance she would put them back on.