At the big flat figures museum in Kulmbach
https://www.plassenburg.de/they used to have a large laundry day diorama in a glass case that had a joke only visible from one side.
Can't recall if it was SYW or Napoleonic, but it featured a patrol (dragoons or hussars?) riding along a street and looking over a wall laughing.
From the front you could see the laughing troopers and a group of laundry maids working in the yard behind the wall, if you went around to the other side of the case you could see the cause of laughter, one of the unfortunate girls, struggling with a large basket of laundry, had managed to drop her skirt and was obviously visible over the wall to the mounted troopers.