I have witnessed another couple having sex only a very few times and It really turned me on. Once after watching a movie, I went to my car in the parking lot. About 4 cars away from me I noticed some activity. The parking lot was almost empty. It was night time. I saw a girl sitting on some guy, facing him and bouncing on his lap. Up and down, up and down. She held onto his shoulders and bounced away. After a few munutes she went down and stayed there and waited a few minutes. Then she got off...pulled down the front of her skirt and they drove off.
Another time at night, I got out of bed to get a drink of water and looking out my bedroom window, I could see in the house next to me my neighbor, naked, bouncing up and down her husbands naked body. She was moaning and palming her naked tits. After awhile she turned around straddled him, spread her ass cheeks and took his erection into her bum. I started fingering my now sopping wet pussy as I watched them until she and he had cum .