I was riding my bike through a public park near my house. The park is huge and has three separate rest room facilities with one of the buildings being at the furthest end of the park. I was near that building when I decided I would take advantage of its location and make a bathroom stop.
As I entered the ladies room I couldn't believe my eyes. In front of me were two women. One looked to be very young, possibly in her later teens or early twenties. The other one looked to be about fifty. The older one had her pants and panties down at her ankles and she was bent forward with her hands on a sink. The younger one was fully dressed and had one of her fingers inserted up into the older ones anus. She was moving the finger in and out of the woman repeatedly. I just stood staring in shock.
I think the young one sensed my presence and turned toward me. She just smiled at me and continued to do what she was doing. The older woman kept moaning and saying, "don't stop, don't stop." The younger one then said, "let's try two fingers." She withdrew her finger and put some soap from the sink onto another finger. Now, two fingers went into the woman's rectum. The older one then said, "that feels wonderful." After about a minute of this the younger one told the older woman that that was enough and she withdrew her two fingers.
As I turned to quickly leave the room the younger one turns to me and says, "would you like me to do it to you?" I just shook my head and left. As I rode to my car this was all I thought about. At home I kept wondering what it would have been like if I had said yes to the younger woman. That night I couldn't wait to masturbate as I imagined a finger or two being pumped in and out of my rectum by a young stranger.