Several years ago, I was working the night shift. Things were very slow, and the boss came in and said I could go home. It was just after midnight. I should mention my wife and I lived in a house that had been split in two, and there was a door which opened so one could go from one side to the other. In the other half lived a young couple. His wife was no real great looker, but had a great body. He, on the other hand, really turned me on. I entered the house and did not see my wife in the bedroom. After a quick look around, I noted the door to their half was open. I quietly went in to hear noise in the bedroom. I peeked in to see my wife giving oral to his wife, while he had his way with my wife. I was instantly turned on. I quietly undressed and joined them. I began by kissing him and this really got him by surprise. After a few seconds, he began to return the kisses. That was the beginning of a two year relationship that we carried on.