Reply: Step daughter

My in-laws are out of town and they live next door, so yesterday afternoon my wife and I walked next door to feed their animals. When we were almost done, I asked my wife for a quicky on their sofa, and, to my surprise she said yes. I quickly pulled off my shorts and underwear and sat on the sofa, my wife pulled off her shorts and panties and straddled me and started riding me.
A few minutes in I noticed some movement behind my wife. I slowly peek around her right shoulder, and there stands her daughter, my step daughter, who is sixteen, watching us with a huge grin on her face. The sex was getting really good, so I didn't say anything to my wife, I didn't want to ruin it. A minute or so later I peek around my wife again and my step daughter is still watching, but now has one hand pushed down the front of her shorts furiously rubbing herself.
A few minutes later, my wife and I both orgasm, and she collapses onto my chest. I grab her tightly so she can't turn around and see her daughter who is standing there licking the fingers of the hand that was in her shorts earlier. My wife starts to push against me, trying to get up, so I motion to my step daughter to leave, and she does.
We get cleaned up, put our clothes back on and walk back home. When we walk in the door, my step daughter is sitting there and she asks, "what took y'all so long"? And she gave me a sly grin as she looked at my crotch smiling. True story.