Answer this question, 2. I hoped to sign the birthday card our team bought for Coach, but I couldn’t find a spot to sign my name because someone went all John Hancock on it and signed his name across the whole card.

Reference to: ______________________________________________________
Possible meaning:

John Hancock is a reference to the large, flamboyant signature of John Hancock, a prominent figure in the American Revolution. The speaker is implying that someone signed their name on the card in a similarly large and ostentatious manner.