Boss invites me to motel for lunchtime rendezvous and asks me to return later with milk

I was sitting at my desk when my boss came in and asked if I wanted to join him for lunch. He said that he had some important business to discuss with me. I agreed and went with him to his car. We drove to a motel and went inside. He invited me to sit down and we started talking about work. Suddenly, he asked me if I could bring some milk later. I was confused and asked him why he needed it. He told me that his wife was coming over later and he wanted to make some milkshake for her. I thought it was strange, but I didn't say anything. I left the motel and went back to my office. Later, when I came back with the milk, his wife was already there. She was very hot and sexy. I realized that my boss had invited me to the motel not to talk about work, but to have sex with his wife. It turned out that my boss and his wife were swingers and they wanted me to join them.