In my case, I told her I have been having these thoughts lately about making love to her and another male friend. We talked openly and I have told her that for some reason I get super excited imagining her taking two cocks at the same time.
And it is true, I get super excited seeig her filled with pleasure and satisfaction, in general.
At first, I was joking and arguing about the fact that if it feels so good for her when I fuck her from behind and if it feels so good for her when she has a cock in her moutth, it should definetly feel good for her when combining these two. Double the cocks, double the pleasure.
We started role-playing like that with a dildo. I told her to imagine that the other cock belong to who ever she wants and she does not have to tell me. She just have to act freely and naturaly.
From time to time we have these role-play games and it is terribly exciting seeing her fucking the hell of that dildo while I have my cock in her mouth.
I think it is a good start 🙂