I was at my local bagel café when the manager asked me: “Where did the term a cup of Joe come from?” The dude with dreadlocks next to me immediately googled “cup of Joe” and we all instantly learned nobody is 100% sure. You have to love google!
One popular theory is Josephus Daniels, Secretary of Navy under President Woodrow Wilson on June 1st 1914 issued General Order 99 which prohibited alcohol aboard all naval vessels. Consequently, the strongest drink aboard all ships was coffee, thus annoyed coffee drinking navy personnel began to call coffee “a cup of Joe.” Is General Order 99 still in effect? Another google search indicated yes, alcohol is still not allowed to be consumed onboard United States warships. However, the only exception to this rule is if the crew has gone more than 45 days since last pulling into a port, then the commanding officer can authorize a “beer day.” The crew would then be limited to consuming no more than 2 beers provided they do not have any duties in the next 4 hours.
English researchers have several theories about the origin of “cup of Joe.” First Joe is the shorten version of two slang words: java and jamoke. Note: The word jamoke was originally the slang created for java and mocha. The second theory dates back to 1836 when “Joe” came into existence as a slang name for “the common man.” Thus “cup of Joe” became known as the “common man’s drink”.
Bottomline: No one is 100% sure of where the term “cup of Joe” came from. This much I do know. Google’s Mission Statement – Organize the world's information and make it universally accessible and useful.
Google: Mission Accomplished!