The term Fool is really a misnomer. The court Fool, although meant to act ridiculous, was the king's most trusted advisor and confidante. Only he had the authority to poke fun at the king and call him out for bad behavior, without fear of losing his head to the executioner. Since jester and Fool are synonymous for the same job, you're complimenting us both.
Professor Kotaro just calmly eats his oysters, while Hana scarfs them down and impatiently begs for more. It's interesting to see how they each have their distinct personality.