I'm rather nervous about posting this as my wife would be very upset if anyone was able to identify her. We have just had a friend to stay, Colin, who is in his early 40's but has never married or even had a girfriend as far as we know. His inexperience became more obvious on his last day with us when, over dinner and a couple of bottles of wine, he admitted that he had never seen a porn movie. We have a few DVDs at home but my wife has never approved and doesn't like to watch them. I was therefore surprised when she suggested that we watch one after dinner. So we settled down in the TV room and started to watch a collection of short movies which were mainly two men with one woman. Colin seemed mesmerised by what was going on and I noticed that my wife was getting very interested. She started to rub my thigh while keeping well clear of Colin on the other side of the sofa. This is what I would have expected as we have both been completely faithful in over 25 years of marriage. Feeling increasingly horny I put my hand up her skirt and began to stoke her thigh. I moved my fingers on to her pussy which was becoming wet, something that very rarely happens to her unless she is very aroused. I began to rub her clitoris and she opened her legs to allow me better access. She closed her eyes and her breathing became shorter - I knew that she would soon come. Both she and I had completely forgotten about Colin. When she came, she said "fuck me now" as she always does at this point but before I could do anything, Colin pulled down his shorts, moved bewteen her legs and quickly mounted her. He had a small prick but it was rock hard and easily slipped into my wife's wet cunt. I was horrified and was about to push him off her when my wife grabbed Colin's hips and pulled him into her in time with his thrustings. I was fascinated to see the look on her face of sheer delight as she began to moan with her eyes half closed. I stood up next to her and tried to put my prick in her mouth but she has never done that and just kept pulling Colin in time with his thrusts. After a few minutes she came again with a grunt which which brought Colin to orgasm a few seconds later. She let him come inside her and when she opened her eyes she pushed Colin away. I thought she would be embarrassed and quickly leave the room but I was surprised when she sid "quick, now you do it to me." I need no encouragement and immediately mounted her in the same position that Colin had used. Her cunt was very wet and I could feel his sperm inside her as I began to pump as hard and fast as I could. She was groaning and panting and I could here the movie in the background making the same noises. It was all too much for me and I came in about a minute. When I stood up I saw that Colin had been wanking himself and was already hard again. My wife quickly turned over into the doggy position, leaning on the seat of the sofa, but Colin seemed a bit confused. My wife sensed the problem and reached behind her to guide his prick into her. He fucked her for at least five minutes while, fascinated, I watched the changing expressions on her face. I think she came again before Colin groaned and made his final thrusts into her. He then pulled out and lay back on the sofa. At this point my wife suddenly jumped up and left the room as if she had just realised what she had done. She went to the bedroom to shower and get dressed and never mentioned the event again. Colin later confessed that he had not had sex since a failed teenage relationship which had scarred him for life and when my wife said "fuck me" he had lost control and pushed me out of the way. He apologised but I told him that while I was although I was shocked by my wife's behaviour, I had enjoyed the whole thing and had no reason to blame him.