The bizarre reason men don’t use the bottom button on suit jackets

History teaches us that a king’s peculiarities can lead to generations of people practicing odd social etiquette. Take, for example, a certain king of Spain who had a lisp. Members of his court began “lithping their etheth” so the king’s affliction wouldn’t stand out. That’s why to this day, upper crust Spanish is still spoken with a lisp.

Okay, that’s actually an urban legend. I mean, who would do something completely nonsensical for generations just to flatter a quirky king who died more than 100 years ago? Well, nearly every man who wears a suit jacket—that’s who!

The Skinny On A Big King

Here’s the deal with that bottom suit button. As suits became the fashion norm for European gentleman in the late 1800s, the English gentry noticed their king, Edward the VII, wasn’t buttoning his bottom jacket button. Why not? Because he was too portly to wear suit jackets buttoned at the bottom. Out of respect for their king, English men started leaving their bottom button undone as well. And to this day, well-dressed men don’t use the bottom button on single-breasted suit jackets. It’s such a widely accepted fashion rule that tailors actually cut suits based on the assumption that the bottom button won’t be used.

M-A-N Up When Buttoning Up

When advising your man (or little brother or nephew) on which buttons to use on a suit, take a cue from men’s image consultant Shane Gibbings-Johns. On his blog, Suitably Inclined, he explains the M-A-N rule of thumb: From top to bottom, suit buttons should be used “Maybe, Always, Never.” This is also referred to as the “Sometimes, Always, Never” rule. This means that a man may sometimes button the top button of a three-button suit jacket, should always button the middle button and should never button the bottom button. For a two-button jacket, the rule of thumb is “always and never.” For a one-button jacket, it’s “always.”

MORE: The Best Ratchet Belts For Men

When do you button the top button on a three-button jacket? It’s a question of personal style, sometimes guided by the lapel, according to Gibbings-Johns. If the lapel covers the button, don’t button it.

When should you use no buttons? When sitting down, a man can prevent creasing and a tight-fitting button from popping off by unbuttoning all of the buttons. Button up as soon as you stand.

With a double-breasted suit, generally button all of the buttons. If you like longer lines, unbutton the bottom buttons, according to fashion website RealMenStyle. To complicate things even more, the rules for sport coats are more flexible because they’re less formal than suits.

Dress For Success

Is it really that important for a man to remember the rules for buttoning a suit jacket? Whether he’s in a job interview or meeting a potential date, a man should dress to impress—because enough people know the rules for buttoning a jacket, so it’s best to get it right.