Talk the hind leg off a donkey
Definition 1 of 1
Pro Tip 1/3Exaggeration
The phrase uses hyperbole, meaning it is an intentional exaggeration not to be taken literally. 
Whenever she tells stories, she could talk the hind leg off a donkey, going on for hours!
Pro Tip 2/3Humorous Tone
It's often used humorously to poke fun at someone's chattiness without real malice. 
I didn't get a word in – you could talk the hind leg off a donkey!
Pro Tip 3/3Context Specific
It's more commonly used among friends or in casual settings, not an expression for formal situations. 
At the family BBQ, Uncle Joe could talk the hind leg off a donkey with his stories.