I have a friend that he and I have swapped nude pics of our wives for years, he is on his 2nd wife, his 1st wife was hotter looking, but he says 2nd wife if more fun sexually. He says his wife, or wives, would kill him if they knew he showed me their pics. My wife knows he has seen her and she loves they idea, although she doesn't want me to ever tell him that.
Some of my very old friends from college days have seen my wife when we all went skinny dipping at a swimming party over 40 years ago. Funny note is that my wife, then GF, was the only one of the girls who have shaved her bush a couple of weeks before the party, that wasn't done then. She got the nickname 'Fuzzy" from that night, she still laughs when someone calls he that.