Fantasy w/ SIL

I had this dream last night that my sister in law caught me jerking off and at first was shocked and blushed but then looked behind her to make sure no one was looking, and said, keep going. So I did. I asked, wanna give me a hand? She said I want to but I can't...my sister is ten feet away. But her breathing got rapid and she said, damn that's a big dick. I asked if she wanted it...she said of fuck yeah I do. I ended up cumming on her yoga pants and she walked back into the kitchen with my cum dripping down her pant leg.

I'm stroking for the third time today thinking about it.