To hope for success. This saying comes from an ancient superstition that making the sign of the cross will avert bad luck. Often put as Keep your fingers crossed, meaning “Wish me luck,” it dates from the 1920s. One writer points out it may also have come from children’s games in which crossing one’s fingers denotes that one is “safe,” as well as the gambit of telling a lie with one’s fingers crossed, presumably to avoid punishment for this sinful act.