I live in a converted warehouse, four stories and forty lofts. There are double walls between the units, a single wall between units and the hallway, and about six inches of concrete between floors. You don't really get much noise from your neighbors unless they're in the hall outside your unit, though certain noises really travel through the floors.
About half an hour ago I was sitting at my desk, and I heard a horrible racket.... grind grind grind grind, and then a thump against the wall. It almost sounded like an earthquake until I heard a similar noise about 20 seconds later, and then another one. Whiskey tango foxtrot?
It kept up for a couple of minutes... grind grind, thump, grind grind... so I threw some clothes on and went out into the hall to see what the hell was going on. I found a kid maybe 12 years old, rolling back and forth along the hall and bumping into walls. "Hey. It's kinda late for that you know. It's really loud, and people are trying to sleep." OK, I wasn't trying to sleep, but that's not the point. I'm sure someone was.
Just as I was saying it, his little brother came cruising around the corner on a razor scooter and bumped into my wall to stop himself. I shot him a look. "It's after 11. People are trying to sleep."
They scooted down the hall and into a loft, and as I went back inside my unit I realized I'd just turned into that mean old lady.