A meek admission of a mistake. The “humble pie” that we eat when we make a misjudgment or outright error was originally “umble” pie made from the intestines of other less appetizing animal parts. Servants and other lower-class people ate them, as opposed to better cuts. “Umble” became “humble” over the years until eating that pie came to mean expressing a very meek mea culpa. A similar phrase is “eat crow,” the bird being as unpalatable a dish as one's own words.