I love all these fantasies, especially those that have become reality.
I fantasize about my wife and I swinging with another couple. All four of us stay in the same room. We play a game where two of us have sex while the other two watch. We agree in advance on what kinds of kinks and sexual acts are OK, and we bring the required gear for the kinky stuff we might do. I'd vote for anything goes, (with a safe word of course.) Ideally all four of us would already be bisexual or willing to try it. We'd all pledge to give or receive either oral and anal sex to or from a man or a woman anytime the game dictates that we must.
To begin each new sex scene, (one of several sex scenes in a series I'd hope), two sex partners are chosen randomly from the four of us by drawing names out of a hat. The other two of us get to decide what kind of sexual things the two sex partners will do to each other, and of course we get to watch and give orders during the scene. For example, one couple might have to sexually perform for the other couple in whatever way the other couple chooses. Or a man and woman from different couples might be forced to have sex with each other in whatever way the other man and the other woman decide. Also, the two women might be forced to have sex in front of the two men in whatever way the men decide. And then there's the possibility that the two women might get to make their men have sex with each other in whatever way they want to watch.
There are so many exciting possibilities. My wife and I might get to command the woman of the other couple to tie up her man and peg him while swatting his butt with a little whip. The other man and I might decide to order his wife to go down on my wife while she fucks my wife's ass with a dildo. I'd love to watch that, (and see if she does it as well as I do.) I can also think of a few ways I'd love to be victimized, and several ways I'd love to be commanded to victimize someone else.
If this game gets boring, we can start drawing three names out of the hat. The first time I got to be the odd man out, I think I'd enjoy watching my wife get tied to a table top so the other woman could fuck her with a strap on while the other man has his way with her defenseless mouth. That would be fun to watch, but then what might happen to me in a future scene when my wife is the odd person out?
Anyone want to play?