A “canard” is a story or a statement that is a hoax or a lie.
Canard is French for duck, but in English the word refers to a deliberate falsehood and is based on a French proverb about cheating or swindling.
Vendre un canard a moitie literally translated means “to half sell a duck.”
However, the expression probably means “to sell half a duck.”
Selling a bag containing a half duck as if it were whole at a busy farmers’ market would constitute a deliberate “lie” with the intention of cheating the purchaser.
The U.S. reason for invading Iraq has been called a canard.