China's president has some words of advice for his country's globetrotting citizens: Eat more local seafood and fewer cups of noodles.

On Tuesday, while on a diplomatic trip to the tropical Maldives, Xi Jinping joked that his countrymen needed to improve their manners when representing their country overseas. "Let me just say here that we ought to teach our citizens to be a bit more civilized when they travel abroad," Mr. Xi said. "Don't throw water bottles everywhere, don't destroy people's coral reefs and...