I don’t know how to bring up swapping or swinging or whatever you want to call it with my wife or them. I fantasize about it all the time. We did all go skinny dipping in their pool but it got broken up, so I never found out what would have happened.
I figured truth or dare would kind of ease everybody into it.
You should have a honest talk about your fantasy with your wife first. Perhaps she is really open to the idea! And if she is completely against it, you shouldn’t try to "sneak" it in.
That being said, if you would want to sneak it in with the support of your wife, playing truth or dare is the perfect game for that.
Ideally, you will want to mix that up with some alcoholic help! Don’t exaggerate, though. Everyone should still be able to remember it the next day.
That being said, I would approach it with the swimming pool again (or a hot tub, jacuzzi or even a spacious bathroom). Relax with some drinks there.
Bring up playing Truth or Dare almost jokingly. If someone objects, play the "are you chicken" card playfully. To ease everyone in, start with smaller dares. Have them imitate each other, tickle, caress, pinch and tease each other.
After you all are comfortable with your touch, start with
– kissing dares
– melt ice cubes in your swimming clothes, between you
– pass them from mouth to mouth
– remove clothing, using towels as cover
– remove those
– resume touching dares
– I will leave up the rest to your fantasy!