The phrase “in the buff” is a playful way to say someone’s naked—but it began with leather. In the 17th century, “buff” referred to a soft, tan leather made from buffalo or ox hide, similar in color to human skin. People began using “buff” to describe that bare-skin tone.

There’s a military twist, too: soldiers wore buff-colored tunics, and when out of full uniform, they were said to be “in the buff.” Over time, the phrase stuck—and took on a cheekier meaning.