Members of the City Watch employ a sort of slang in dealing with the public. As a visitor, it behooves you to know what they mean.
“What befalls?” means “Someone tell me what’s going on here.”
“Hold!” means “Don’t move a muscle.”
“Down arms!” means “Drop your weapons.”
“Talk truth!” means “Answer me” or “Tell the whole story.”
“Robes” references the black robes — in other words, one of the magisters. “Do we need robes here?” or something similar should be taken as a threat.
“Goodsir” and “goodwife” are the terms members of the Watch use to address adult citizens.
“Jack” and “goodlass”  are the terms members of the Watch use to address younger citizens.
“Gentlesir” and “goodlady” are the terms members of the Watch use to address Waterdhavian nobility or diplomatic guests. Mixed-gender noble groups are addressed as “gentles.”
“Sir” or “sorn sir” is the all-purpose formal form of address when members of the Watch speak to superiors.