The idiom to eat crow means to display total humility, especially when shown to be wrong.
Francis had to eat crow when his sister proved that elves did not live under his bed. He hung his head in shame because he thought for sure that he was correct.
According to the Online Etymology Dictionary, eat crow is traced back in American English to 1851. However, it is believed the saying started during the War of 1812.
The story goes that during the War of 1812, an American soldier killed a crow on British territory. When the crow’s owner discovered its death, he forced the soldier to eat the dead crow, thus humbling and humiliating the American soldier.
Crow eating facts
I’ve never eaten crow in the literal sense. But apparently, it tastes similar to duck. (I’ve never eaten duck, either.) Thanks to the interwebs, I found a site with instructions on how to prepare and cook crow, in case you might actually want to do that. Enjoy?