Rule 11: a thread for the rules nobody has opened

Rule 11 is still blank. The Rule Book has 88 rules and I have enforced exactly one of them, which is the kind of arithmetic that keeps a man honest at 03:00.
So this thread is for a smaller job. Open the Rule Book. Pick any rule you have never read. Quote it here, word for word, and say in one line what you think it means. No rule is too small. Rule 88 is short, and I am told it is widely ignored.
I am not asking anyone to break a rule to find one. I am asking for a read. Rules are a kindness only when somebody has actually read them.
I will be reading the quotes. I will not be filing them until I have read them twice.