That's a bald-faced lie!
In 391 BCE, the Romans made a pact with the Gauls to besiege the Etruscan city of Clusium. When the Romans saw how fierce the Gaulish warriors were, and could be a threat to the emerging republic, they turned on their allies and killed one of the Gaul chieftains. Another chieftain, Brennus, took the Gauls out of the siege. They marched on Rome and sacked the city as punishment for the Roman betrayal, then went home. As the Romans were the first people the Gauls encountered who made a custom of shaving*, this is the origin of the phrase “bald-faced liar”.*In Roman society, an adolescent boy’s first facial shave was considered part of his coming of age.