Last sunday I went to my wife's sister's house. I had just come from a jog, and my wife suggested that I take a shower. I went into the bathroom and found my sister-in-law's panties. I felt so horny....I think that she suspects that I wank with her panties as she once 'insisted' that i use the bathroom. I have seen her naked as well, and she is gorgeous (very hairy pussy...just the way I like it). Anyways, I took her panties and wrapped it around my hard cock...and masturbated...waiting to hear her voice in the other room. I timed my cum so that I shot my load as she laughed loudly in the other room.