What is the origin of the idiom "talk the hind leg off a donkey" and when to use it?

The origin of the phrase "talk the hind leg off a donkey" is not definitively known, but it likely emerged as a humorous and exaggerated way to describe someone's excessive talking. The phrase itself is colloquial and informal, and it has been in use for many years as a way to emphasize the talkativeness of an individual.