Definition Of quacks
(of a duck) make a characteristic harsh sound.
Yet, in case after case, the chicken always ended up dead, while the duck went happily quacking down the river.
a person who dishonestly claims to have special knowledge and skill in some field, typically in medicine.
the characteristic harsh sound made by a duck.
But even from the vague hints he throws out, I think we may rest assured it will not be the last quack of a lame duck.