* The Unexpected: Do something completely out of the ordinary. Maybe wear a silly hat, sing a silly song, or do a funny dance.
* The Silly Joke: Tell him a joke that is so bad, it's good. Like: Why did the scarecrow win an award? Because he was outstanding in his field!
* The Gentle Approach: Show him kindness and try to understand his grumpiness. Maybe he's lonely, or something is bothering him. Offer him a cup of tea and a kind word.
* The Laughter Contagion: If you can get someone else to laugh genuinely, it might be contagious. Perhaps a jester or a court fool could do the trick.
Remember, the key is to be genuine and lighthearted. Even the grumpiest king can't resist a good laugh!