In the third Indiana Jones Movie Indiana Jones and the Last Crusade there's a scene in Indy's classroom where he tells his students that X almost never marks the spot. And in a lovely poetical moment later in the film X, indeed, marks the spot--or in this case the Roman numeral for 10 (aka X) marks the spot.
It was was clever way to make a sometimes arrogant Indy eat his words.
Have you ever had to eat crow? How about your characters? Are you one of those mean writers who sets up your character's credibility only to crush it with a humility smack down?