Here's a "it didn't happen" note from Wikipedia's article on the "John Adams" miniseries:

John Hancock is confronted by a British customs official, and he orders the crowd to "teach him a lesson, tar the bastard". Hancock and Samuel Adams then look on while the official is tarred and feathered, to the disapproval of John Adams. The scene is fictional and does not appear in McCullough's book. According to Samuel Adams biographer Ira Stoll, there is no evidence that Samuel Adams and John Hancock, who were opposed to mob violence, were ever present at a tarring and feathering, and so the scene succeeds in "tarring the reputations of Hancock and Samuel Adams".[22] Jeremy Stern writes, "Despite popular mythology, tarrings were never common in Revolutionary Boston, and were not promoted by the opposition leadership. The entire sequence is pure and pernicious fiction."[17] According to Stern, the scene is used to highlight a schism between Samuel and John Adams, which is entirely fictional.[17]