It's a well-documented style rule that men should never button the second button of a two-button suit jacket. It's considered appropriate to button the top one when standing, sure, but never the second.
So if no one's supposed to use the bottom button, why does it exist?
As with many fashion curiosities, history reportedly factors in. Legend goes that Britain's Edward VII ― a king with several famous appetites ― grew too large for his suit and had to stop using the second button as a result. Not wanting to embarrass him, others followed. The tradition stuck.
Other theories include dandies who wanted to show off multiple layers of clothing, the comfort of horse-riding in a suit, and the favored style of an exclusive club at Eton. But GQ's UK fashion director Robert Johnson said he favors the Edwardian theory, correctly pointing out "there is nothing so weird as court etiquette."
Nowadays, men's suit jackets typically have two or three buttons, though some are made with one. The "sometimes, always, never" rule for three-button jackets states that you should sometimes button the top button, always button the middle one and never use the last button. On a two-button jacket, you should always use to the top button and never use the second.
Whether Edward VII was the true inspiration for this or simply makes for a convenient tale, modern suits are now tailored to fit with the last button unbuttoned ― using it makes them both look and feel too tight.
"It induces a tension in the jacket that feels restrictive," Clive Dilnot, a professor of Design Studies at The New School, told HuffPost.
Many men choose to leave their buttons undone altogether, Dilnot added. In the official style playbook, it's acceptable to undo all the buttons before sitting to avoid pulling and tugging the fabric, according to menswear site Black Lapel.
Ahh, sweet release. Thanks, King Ed!