pet-form of Joseph (q.v.). Meaning "generic fellow, man" is from 1846. Used in a wide range of invented names meaning "typical male example of," for example Joe college "typical college man" (1932); Joe Blow "average fellow" is U.S. military slang, first recorded 1941. "Dictionary of American Slang" lists, among other examples, Joe Average, Beige, Lunch Bucket, Public, Sad, Schmoe, Six-pack, Yale, Zilch

joe (n.)

"coffee," by 1941, perhaps late 1930s, of unknown origin. The guess that it is from the name of U.S. coffee merchant Joseph Martinson (c. 1880-1949) is not chronologically impossible, but it wants evidence and seems to have originated in the company's advertisements (1972). Earlier in American English (1772) it was the colloquial name of a Portuguese or Brazilian coin worth about $8, shortened from Johannes in this sense (1758), the Modern Latin form of Portuguese João (see John), name of a king of Portugal whose head and Latin inscription appeared on the coin.