Jimmy: Bobby Woodward owes me a favor from way back.
Matthew: What, were you like Deep Throat or something?
Suspiciously, Jimmy doesn't answer this question. This is the longest running gag in the series implying that Jimmy was indeed the famed Watergate informant. Deep Throat was the nickname given to Woodward and Bernstein's inside source during their investigation of the Watergate scandal. Woodward was frequently asked the identity of Deep Throat, but he said that he had promised not to reveal his source while the person was still alive. In 2005, Mark Felt, the Deputy Director of the FBI during Watergate, came forward to say that he was Deep Throat. Woodward confirmed this.