We're in apartments and the layout of these units are the same as the next, just stacked really. So our bedroom is directly below the upstairs neighbors bedroom, as goes for the rest of the place and our 2 other bedrooms. So keeping this in mind, while DH and I were going to town the other night, we all of the sudden hear our neighbor upstairs walk into his room with some girl and we can hear them yelling but we try to ignore it...then all of the sudden we hear this machine turn on (which sounds like a basketball bouncing really hard on their hardwood floors) and before you know it a loud vibration starts to follow. DH and I were thankfully already good at that point but we laid in bed laughing trying to guess what the hell they were using. Apparently their angry sex involves some form of heavy device, loud enough to shake the walls. Gotta love renting!