Three Famous Johns in UK & US

* John Barleycorn

the personification (= the representation of a thing as a person in literature or art) of alcoholic drink, especailly strong drinks such as beer and whisky. "John Barleycorn" is an English folksong. In the song, John Barleycorn is represented as suffering attacks, death, and indignities that correspond to the various stages of barley cultivation, such as reaping and malting.

* John Bull

a typical Englishman, who is thought of as representing Englishmen in general. John Bull is shown in pictures as a large. fat man wearing high leather boots and a waistcoat with the pattern of the Union Jack on it (= the national flag of the UK) and there is often a bulldog beside him. He is thought of as being very proud of England, and as disliking foreigners.

* John Hancock

a signature 8your name as you write it on documents,cheques, etc.) this meaning comes from the story that John Hancock wrote his name in very large handwriting on the Decvlaration of Independence as an insulting joke to the British king, George III, so that the king would not have to wear his glasses to read it.