Although my wife is in good shape and her sister is a little chubby, they still look pretty much alike. For being in their upper thirties, both are still pretty attractive. The four of us spent the holiday weekend in a chalet together. We cooked fish on the grill and had lots of wine. Everyone got in the mood. Our wives said they were going to their respective bedrooms to prepare for when we got there after finishing cleaning up. When I got into our bedroom, indirect light from a candle barely allowed me to see my wife bending over our bed. In her thongs and poor light, her behind looked so luring. I quietly got closer and surprised her by licking her buttocks from behind. She moaned slightly and told me to continue. I gave her a full oral from behind. When she got aroused enough, I removed her wet thongs and flipped her over for kissing and fondling only to find out, a little late, that I had been doing all of this to my sister-in-law. I apologized and headed back to the other bedroom to find my wife asleep. My brother-in-law was reading a magazine in the living room. I didn't want to ask questions. -Byron, 41