My downstairs neighbor fucked loud and hard at all hours. Pic related. The floor/ceiling between her unit and ours was incredibly thin. She would occasionally have a girl over and we could hear them moaning and cumming, so neighbor must've been bi. Once I heard a threesome with another guy and girl. My girlfriend at the time got turned on hearing her as much as I did. We would occasionally start fucking at the same time. Gf would love to fantasize that our neighbor would hear us and get turned on as well.