When I was younger, single and living a block of flats I would often open my window and start fingering myself and moaning really loudly. It would make my orgasm even more intense when I thought about how my neighbours could hear me moan and whimper.
I guess it was a form of voyeurism. But now I'm older and braver having sex in a public place or risky place is a huge turn on for me. I've only done it a few times but I would definitely like to do it more. Much more!