The most humiliating experience for me/us was a few years ago, pre covid and M had a regular bf/bull. We all got on quite well and after a few months he invited both of us to his for a BBQ/party. It was pretty chilled but he told M to wear something sexy and small.
When we got there it was a lot of his friends, all very relaxed, but we were the only white couple there and it was obvious that he had told his friends what the deal was. Everyone was very cool and chilled but knowing that everyone there knew we were both staying over and he was going to be fucking my Mrs was definitely on the humiliation scale.
He turned up up a notch as the evening wore on by openly kissing her. A bit later when there were only a couple of folks left, he walked her to his room while cupping her ass, left the door open and fucked her. Apparently they decided this would be a fun thing to do. While they did that I chilled in the living room with the guys who were still there and they were asking me questions about the whole thing and situation. That was probably the most surreal part