A lot vs. Alot: 9 Grammatical Pitfalls
colloquial for "signature," 1903 (sometimes, through some unexplainable error, John Henry), from the Boston merchant and rebel (1736-1793), signer of the U.S. Declaration of Independence. The extended sense is from his signing that dangerous document first or most flamboyantly.
John Hancock, president of Congress, was the first to sign the Declaration of Independence, writing his name in large, plain letters, and saying: "There; John Bull can read my name without spectacles. Now let him double the price on my head, for this is my defiance." [Hélène Adeline Guerber, "The Story of the Thirteen Colonies," New York, 1898]The family name is attested from 1276 in Yorkshire, a diminutive (see cock) of Hann, a very common given name in 13c. Yorkshire as a pet form of Henry or John.
[1903+; fr the fact that John Hancock of Massachusetts was the first to sign the Declaration of Independence in 1776; John Henry, possibly by confusion with Patrick Henry, because of the prominence of John Henry as a folklore hero, and by near-rhyming resemblance]