According to French legend, the Duke of Lorraine and his wife were imprisoned at Nantes. They escaped on April 1, 1632 by disguising themselves as peasants and walking through the front gate. Someone noticed them escaping and told the guards. But the guards believed the warning to be a "poisson d'Avril" (or April Fool's Day joke) and laughed at it, thus allowing the Duke and his wife to escape.

This story is occasionally offered as an early example of the custom of April Foolery. However, there is no evidence the story is true.