My wife's brother got married last year and I a mutual friend arranged for a secret "last nite out" bachelor party - none of us let our wives/girlfriens know where we were going. The party started by hitting a few strip clubs and ended up at a big hotel suite with some private strippers and a ****** available in one of the darkened bedrooms for any of the guys, and 3 or 4 took advantage.
In the weeks after the fantasy emerged of me being asked to provide the ******, and the night of the party the woman backing out. My wife has a fantasy of being gangbanged (though she says she could never actually do it), so my devious mind pushes me to tell her that I've set up her fantasy with some friends, though they don't know it is her they'll be fucking. Seemingly "pushed" into it makes it easier for her to let the fantasy happen. She's blindfolded and naked in the dark room, and the grom gets first crack.
The next morning, as my wife sleeps after fucking 6 guys, I watch the night vision video of her fucking her brother nareback and neither know who the other is. I imagine I'd cum without touching myself hearing her moans, cries and and orgasm more intense that any I've given her, and knowing that her brother's seed filled my wife..