A recent trip to my gynecologist reminded me of this thread. Swinging is a new thing since the last time I saw her. She knows I'm married and plan to have kids, so she was surprised when I asked for an std screen. I stammered something about sexual contact outside of my marriage.
She: Long pause. "so, is your marriage going to last?"
Me: "Yes... It was his idea."
She: "But,

, WHY?"
Me: "..... cuz, uhm, he thought it'd be fun?"
She: "But, WHY?"
Me:
She: "Well, never mind. Do you enjoy it?"
Me: "Yes!"
She: "Well, as long as you enjoy it, who am I to say no?"
Some minutes and a speculum later (sorry if that's too graphic but I doubt this is a particularly squeamish crowd), I felt the need to further emphasize that I was NOT cheating.
Me: "Well, he's there at the same time."
She: "All three of you together? or more of you?"
Me: nodding
She: "All three?"
Me: "Yes."
She: "And more?"
Me: "Uhm, sometimes."
She had something to talk about at lunch that day!