Say hello to Josephus Daniels, former secretary of the US Navy and namesake of the proverbial cup of joe.
Joe is, of course, short for Joseph. And in American English, “joe” can refer to an average guy, a soldier, or—somewhat strangely—coffee.
As it turns out, the use of joe as slang for coffee dates to the World War I era. It was then that Daniels, who started his career as a newspaper publisher in North Carolina, became secretary of the Navy under president Woodrow Wilson. Daniels tried to imbue the navy with a strict morality. He increased the number of chaplains, discouraged prostitution at naval bases, and, most controversially, banned the consumption of alcohol.
“As a substitute, stewards increased their purchases of coffee, among other beverages,” writes Lee Craig in the new book, “and Daniels’s name became linked to the daily drink of millions around the world. A cup of coffee became disparagingly known as ‘a cup of Joseph Daniels,’ and as legend has it, this was soon shortened to a ‘cup of Joe.’”
Source: Quartz