What is the strangest rule you had to follow at someone else's house?

I had a friend when I was young and their family had a rule that meals were silent. So if the salt or gravy ended up out of reach, you just weren't going to get any.

I also had an aunt who only allowed one quarter of a teaspoon of sugar in tea on weekends and special occasions. Everyone had their own way of sneaking in a bit of sugar from their bags or pockets when she wasn't looking lol