A: Mary had to eat crow yesterday.

B: Why?

A: She talked to her new neighbor Joe as if he was an uneducated idiot, until she found out he was a professor.

Note: Eating crow is an American idiom, meaning humiliation by admitting wrongness or having been proven wrong after taking a strong position. Crow is presumably foul-tasting in the same way that being proven wrong might be emotionally hard to swallow. We have similar idioms such as “eating dirt” and “eating your hat.”