Curry favour

This is a fantastic example of a phrase mutating through mishearing. It comes from a 14th-century French satirical poem, the Roman de Fauvel, about a cunning, corrupt chestnut-coloured horse named Fauvel. To "curry Fauvel," literally to groom the horse, became a figure of speech for sucking up to a powerful but flawed authority. "Fauvel" doesn't mean anything on its own in English, so over time English speakers reshaped it into a word that did: "favour."