Unsurprisingly, this diplomatic mission turns into a pissing contest between Jaime and Euron. As King of The Iron Islands, he will offer Cersei the Iron Fleet, in exchange for her hand in marriage. (That dig about "1000 ships and two good hands" did not go unnoticed. All hail Euron, King of the Shade!) Cersei declines — she doesn't want to marry someone who killed his own brother. His answer is the equivalent of Chekhov's gun: "You should try it, it feels wonderful." No way that doesn't go off somewhere in the season, although whether he means Tyrion or Jaime is anyone's guess at this point.