Why do we cross our fingers for good luck?
Early Christians were widely persecuted in the Roman Empire, and one theory is that the sign began as a secret way of showing your faith and recognising fellow believers.
Its modern association with good luck probably originated with Christians calling ton the sign of the cross for protection.
Crossing your fingers when you tell a lie, meanwhile, may have started out as a way of calling on the cross to protect you from being punished for fibbing.
Answer by Giles Sparrow.