Jon Stewart has been something of a ghost since the end of The Daily Show, popping up only to do the odd guest spot on the shows of former Daily Show correspondents. During the party conventions for the presidential election, he dropped into The Late Show With Stephen Colbert to do watery spit takes with Colbert's old persona and to deliver a pretty epic rant about the importance of this election.
Monday night, as Colbert did a live show on CBS, Stewart returned to the show as "the Mayor of Candytown." He arrived just as Colbert and a street urchin finished singing a song about voting. They reprised the slightly slanted song with a little help from Hamilton's Javier Munoz, elucidating the importance of taking part in the election.
Importantly, they also brought back the egregious spit take, which is probably not Colbert's favorite thing to do on a live show. In fact, it was such a ridiculous thing to Stewart suggested they do it a second time and it made Stewart break like he was SNL-era Jimmy Fallon.