WHAT'S HAPPENING ON THE GROUND FLOOR OF MY APARTMENT?

I live in a 3-story apartment building in Brooklyn. My roommates and I live on the second floor and my landlord lives on the third. We still have no idea who or what lives on the ground floor. Here are a few of our theories:
  1. A GED class
    Evidence: There's a sign on the front of our building advertising GED classes. I've never seen any adults going in there, so I'm not sure if they're just off-season or if they're too lazy to change the banner.
  2. Day care/Summer camp/Pre-school
    Evidence: Sometimes there are kids down there during the day, but this only seems to happen for one week at a time every couple of weeks. Where do these kids go? And what is this space for when they aren't there?
  3. Kickboxing classes
    Evidence: I recently saw a sign on the door that advertised kickboxing classes, but when I looked in through the window there was just one guy sitting at a folding table in an empty room watching Netflix.
  4. My landlord's sex dungeon
    Evidence: The first time I heard the noise from these "kickboxing classes" I thought it was my landlord having very loud, kinky sex. I still haven't ruled out the possibility.
  5. A front for a very low-level drug cartel
    Evidence: None. But this is usually a go-to answer, right?
  6. Rehearsal studios that are free for tenants
    Evidence: Does wishful thinking count as evidence?