treasure
Explanation
The Joke
A pirate captain presents what he calls "the greatest treasure of all" to his crew. When opened, the treasure chest reveals... a friend, who declares "There be only a mirror" (implying the greatest treasure is the viewer themselves -- i.e., friendship). The captain confirms: "That's because the greatest treasure is friendship!" and hugs his crewmate. But the punchline comes when the captain then asks "So can you stop keel-hauling us when we forget to say 'yes sir'?" to which the now-annoyed pirate replies "No, m'lady, no."
The comic subverts the classic "the real treasure was friendship all along" trope that appears in countless children's stories and adventure narratives. The pirate captain tries to use this sentimental cliche as a way to get the fearsome pirate to stop brutally punishing the crew (keel-hauling -- dragging someone under the ship -- was one of the most severe naval punishments). The pirate is completely unmoved by the emotional manipulation.
The Humor
The humor works through the contrast between saccharine sentimentality and pirate brutality. The captain's attempt to weaponize a children's-story moral ("the greatest treasure is friendship") as a negotiating tactic against actual violence is both clever and doomed. The pirate's flat rejection -- maintaining that friendship is great but keel-hauling will continue -- is funny because it shows the complete failure of trying to apply feel-good platitudes to a genuinely dangerous situation. The "m'lady" address also hints that the captain may have set up the whole elaborate treasure-chest scheme specifically to try to soften the pirate's discipline, making the rejection even funnier.