This happened about 5 years ago.
My wife has a younger girl friend, she was then about 42. I'll call her 'Carol'. A real gorgeous woman, blond, tall, leggy, great ass, but smallish titties. I always got along real well with her, kidded around, very little flirting, but some. When she was around I could not stop looking at her. I definately had a thing for her, but knew that nothing would ever happen.
To get to the story: We were all packed up to move from one town to another some 200 miles away. So Carol invited us to spend our last night with her and her husband, they lived nearby. Two things happened that got me incredibly horny. First, that night my wife and I had gotten into bed. Their bathroom was right next to our bedroom, with our bed real close to the bathroom door. We were ready to fall asleep when she came into the bathroom for a final pee. Well, I never thought that listening to her pee would get me that horny! I could hear everything, from her taking her pants down, sitting down, and then that great gush coming out. Finally the flushing of the toilet. I had a huge hard-on, but my wife was right next to me and I could not do anything about it. I still remember that.
But if that turned me on, I was to get even more so the next morning! Her husband went to work very early. Then the rest of us got up. We had breakfast, then my wife and Carol went outside to feed the horses. I was all alone in the house. Immediately I went into my 'look for her soiled panties' mode. I had the place to myself. And I could check outside to be sure they would not come back inside and catch me. It did not take long. I went into their bedroom, and right away I saw my treasure! There on the floor, in plain sight, was a rolled-up pair of her panties! I picked them up, put them in my pocket, and went to the window where I could see the two of them feeding the horses. I took her panties and unrolled them. I still remember they were plain cotton, with red and blue little flowers all over them. I sat down by the window, and put the panties up to my nose. The aroma was incredible! I felt like I was smelling her actual pussy! She obviously dripped alot. I had the most amazing orgasm I have had in years. Remember I was about 57-years-old then. Lots of cum, and an absolutely intense feeling on my cock. All this time I was sniffing her panties, and watching her from afar.
I wanted so badly to take those panties with me, but I knew she would know. I still masturbate to that experience.