My wife asked me to deliver some outdoor Christmas lights to her parents home last week. Her father had forgotten them after my wife and he had gone shopping to the mall together. When I got to his home I knocked but got no answer, so after knocking again, I let myself in using the spare key I had.

Kevin lives on his own now since his wife and my wifes mother died two years ago. So hearing the very unmistakeable sounds of sex coming from his lounge was unusual. I very nearly turned around and walked out, and maybe I should have, but curiosity got the better of me and I peered into Kevins lounge.

My father in law was sat on his couch naked and also naked was a guy around my age. He was facing away from me and bouncing up and down, making all sorts of noises and saying "Yeah fuck me" as his asshole enveloped my father in laws very large cock. It was something I would have never thought about my father in law, because if you knew him, you'd know just how much of a rugged hard man he is.

I carried on watching them for a couple of minutes and began to get the feeling I used to get, when I for a time fooled around with a guy in college. We'd given each other hand jobs and blow jobs and I'd once let him put his cock inside my ass, but it was too painful back then. My cock was hardening and I knew if I stayed any longer I'd have to let them know I was there and not only that, I was horny.

As I was about to leave, Kevin moved the guy to one side and looked right at me, then said "Like what you see Dan". As he said it his lovers ass slid off Kevins cock and I could clearly see just how big my father in laws cock really was. I also saw the glint in his eye as he put his cock back into his friends waiting hole.

He'd known all along I was there and had just carried on anyway. Embarrassed and feeling slightly ashamed of interupting something that was no concern of mine, I left the house. I'd only driven five minutes when my cell phone rang. It was Kevin and he asked not to say anything to my wife, he also said thank you for not causing a scene. As a passing final coment he added "If you wanted to join in, you should have said, maybe next time eh!".

Well next time will be tomorrow as my wife and I visit. My wife will do what she always does, stay for a little while before leaving us to watch football, when she visits her friend for a few hours. All week, all I've thought about is my father in laws big cock and it's driven me crazy with lust. Inevitably we'll got onto the subject of what I witnessed last week, and I just know if he asks me directly, I'll be more than prepared to have some fun with him. I'll have to wait and see what happens and where we both go from there.