I was at a wedding in San Diego at this mansion like property in the Golden Hills district of the city that dates back to the 1880s. The guests were all given rooms for the night of the wedding and because of the ancient architecture of the building that was a turn of the century house, some of the closets connected. I told this to a friend of mine and we agreed to purposely place ourselves in the closet used by the bride and groom. We shared this with a woman who had been for 5 years with our knowing her, a Platonic friend, and she totally wanted to be in on it. So for an hour, the three of us watched the bride and groom on their wedding night. I suppose that qualifies for the "something you shouldn't have seen". The voyeurism got the three of us horny, and we ended up going to the bedroom she had been given for the weekend. We didn't have a full on MFM
but the three of us did play with one another to somewhere between 2nd and 3rd base. (We also had bf and gf relationships we were all a part of, so we didn't cross that line.) We got to enjoy watching the newlyweds in a few fun positions. I suppose you're not supposed to see a newly minted husband and wife on their wedding night, but we couldn't help ourselves.