Source, in full
Quoted in "John Hancock and Bull Story" at snopes.com as one variant of traditional anecdotes of Hancock's purported exclamation at signing the United States Declaration of Independence; there are actually no contemporary or credible accounts of any of the signers declaring anything at the signing.
Notes from Wikiquote
There! John Bull can read my name without spectacles and may now double his reward of £500 for my head. That is my defiance. | The British ministry can read that name without spectacles; let them double their reward. | King George can read that without spectacles!