I have had two memorable experiences. One was MANY years ago, at a truckstop motel just outside Birmingham. (England, NOT Alabama) It was a warm afternoon and my room window was open. I guess the room next door had its window open too, because I could hear them satisfying each other.
I had to make do with satisfying myself. So, arousing and annoying.
The second was 4 years ago, on a caravan site in North Wales. We were there for the week but several others only stayed one or two nights.
This included 2x females, in their late 20's or early 30's, who were using a tent and had pitched it next door to us.
We had gone to bed and my partner was asleep when I heard sex sounds. Sounds that appeared to be emanating from the girls tent!
Instant arousal but, this time I was unable to "join in", for fear of disturbing my partner. She would NOT have been happy, if she had caught me being pervy.
Needless to say, she unknowingly benefited, the next morning! I was hoping for a second night but, when we returned later in the evening, they were gone.