We were at a party at some friends house about 15 years ago. One of the other guys there said to come with him because he wanted to show me something. He took me down to this guys sex dungeon. It was bizarre. We never hung out with those people again.
Early in our marriage, my wife and I were invited to dinner by another couple in the neighborhood. We didn't think much of it, figured they were neighbors that wanted to get to know us better.
Turns out they indeed wanted to know us better. They were "swingers" and though they discreetly danced around the subject for a while, we eventually figured out what they were getting at. The clincher was when, after dinner, they invited us to their living room for drinks where there were two "love seat" couches. The couple immediately sat down separately on the two couches, leaving us no choice but to sit with the other's spouse. This went on rather awkwardly for about 10 minutes until I looked at my watch and said we had to be going as the babysitter had to be gotten home.
Never called them again and they never called us. Creepy!