It's already happened for me, though it was quite some time ago. It was a turn on knowing it turned her on and I believe that turnabout is fair play. I found the idea of her going down on another woman to be hot. She said she liked the idea of me going down on a guy. She got her fantasy first.

It was a fun time. (And seeing her go down on him while I took her from behind was pretty dang hot too. )

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Put me on wheels and I'll turn tricks.

Clever? Nah, I ran out of that years ago. But if you find this, let me know, k?
"The road goes ever on..." ~ Tolkien

In memory of my friend skip...
Go then, there are other worlds than these