You had earlier splashed him with the contents of a chamberpot, which had forced him to cross the line he'd painted earlier in chalk on the ground. This had made him lose to Jang Uk and not be ableto retrieve Jang Uk's family sword, for which he'd come. Now the Crown Prince Go Won is pissed at you for that grave offence, as his robe stinks of piss. He wants to have you punished for that insult.