My wife and I went through a hot wife stage about ten years ago during which time we had six threesomes with two different guys. In addition she had a guy she saw 20 times by herself (I never even met him) and did several solos with our threesome partners.
For the first threesome, we meet the guy for drinks and appetizers a few days before and then on the day in question I dropped her at the hotel with the intent that they could spend some time alone before I joined them. I remember telling my wife I would return in an hour and that she had better not keep me waiting when I knocked on the door, no matter what she was engaged in at the moment.
And she did come to the door quickly when I knocked, stark naked. We kissed and walked into the room where "Jay" was laying naked in the bed. He reached out to me and we shook hands and said "Hi!".
Any that, my friends, was the most surreal moment of my entire life.
We continued, now in full threesome mode. When he had finally had enough, he went over to the sofa and relaxed while my wife and I fucked doggy style.
And that was the second most surreal moment of my life.