I share my wife with a few friends of mine. One night after the 3 of us triple teamed her we were having drinks and my wife asked my friends what they would like to try that they never did before. One friend said to do a pair of sisters. My wife said, "to bad I don't have a sister". and started laughing. She asked the other friend and he said to do a mother and daughter 3way,
Her first response was, "Don't even think about" referring to our daughters then started laughing. But then she said, something alone the lines of, "well, if one of them were into it and wanted to do it one day when they were old enough, she would."
I looked at her and said, really? And she said again, "sure if one if them wanted too," My friend immediately said, "I'm down." and that made everyone laugh. My wife then asked me if i'd be okay with it to which I said, it that's what the girls want, one day when they are older, I guess so. My wife then asked, "but would you want to watch?" And I couldn't lie, so I said yes I would watch.
We f***** again after that and I think the idea of that fantasy turned everyone on so much, it was one of the best times we ever f***** her.