Don't 6
A while back I found this delightful little book in one of my local gift shops. Don't: A Manual of Mistakes & Improprieties more or less prevalent in Conduct and Speech was originally published circa 1880. Rules of etiquette cover At Table, In Dress and Personal Habits, In the Drawing-Room, In Public, In Speech, In General, and my personal favourite, Affectionately addressed to Womankind. Some of the rules still apply, and some don't, which makes it fun reading.
So I've created a new category, Don't, and every now and then I'll scan one of the rules and post it here. Here's today's Don't: