In our old appartment complex one side of the building had a large balcony spanning across all apartments. It was separated with frosted glass but through some big gaps and reflexions on the glass it was possible to see into the other balcony and the room behind.
One evening I sat on my balcony in the dark with my phone out when I noticed the neighbour turned his lights on. He openend the door and I could hear he was with his girlfriend. So I turned my screen off and positioned myself in a way that I could see them through the reflexions. With their room brightly lit I could see them quite well and figured that they probably wouldn't see me. They were both mid 20s, she was petite, with very long blonde hair.
Normally he would close the blinds the second the sun goes down and there was never anything to see. But this evening they both seemed to be a bit drunk and left them open. They started fooling around and eventually ended up kissing. He slid his hands down her tight jeans and grabbed her ass. Then he pulled her jeans down and revealed her beautiful ass in a tiny G-string. As he grabbed the string to pull it down she stopped him and said something. I didn't really understand but I guess it was something like "let's go to the bedroom" because after a kiss they disappeared and the light in their bedroom turned on. Unfortunately because it was to far away the angle made it impossible to see into the bedroom.
After a short while I heard her moan and listened to them fucking for a few minutes. Which was still great but I was so close to also see them