The Kinky Couple on the Train

One year ago, I was sitting next to a couple on the train. We started talking and found out that we actually lived very close to each other. We exchanged phone numbers and I thought that nothing would follow.
Two days later, I got a call from M, the woman of the couple, asking if I was in the mood to meet them in a bar downtown. Of course I liked the idea since they were very friendly people. We met and after some chat they told me that they were married but also a cuckold couple, and that S likes to watch his wife having sex with others and join in later. I was afraid and fascinated at the same time, since I've never been in such a situation before, but my fear disappeared when beautiful M. told me that it was her idea and her husband agrees. They'd already booked a hotel room around the corner and so we went there.
We spent several very hot and horny hours together before she expressed her next desire, asking if we two guys would be able to come one more time. She told her husband and myself to come on her face because she wanted to surprise the bartender. I had no idea what her plan was, but her husband just smiled, knowing what was about to happen. After she had our last drops of cum on her face, she got dressed, put some lipstick on and went back down to the bar, still with our cum on her face. She returned with a bottle of champagne. She smiled and said that this was her very kinky way to convince the bartender to spend the night with us.
Before he arrived, she tied both of us up with bathrobe belts so that we could only watch the fun she was going to have with him. After a while we were freed and all four of us spent the rest of the night together... We've continued to meet up since then. The magic continues...