I don't know how to go about saying this? But your sister is great at oral pleasure! (Yikes) I know this personally. It happen on a day,when drinking gets involved. Too many beers for all of us. You had too many to handle,so you fell asleep on the couch. Later that night,your sister and I took a dip in the pool. Neither of us had swim suits,so we both ended up naked in the pool. At some point,my (johnson) grazed on her leg,or another part of her body,not sure which because of the beers we had chugged down. As we was getting out of the pool to go inside to dry off. I guess she like what she saw. One thing lead to another. I'm sorry