"Fingers crossed" isn't just a common expression (or our favorite emoji). It's one of the most popular and enduring superstitions still used today. And as is the case with many other superstitions, a lot of people who believe in it have no idea how it started. This superstition is so pervasive that, even if you haven't intentionally physically crossed your fingers, you may have used the expression in conversation (probably when talking about something good you want to happen in the future). But crossed fingers aren't just a way to show hope or ask for luck — if you discreetly cross your fingers behind your back, that can mean that you just told a lie. These motives might seem pretty different, but it actually makes a lot of sense that they share the same gesture. In both cases, you've called upon a higher power — whether or not you knew you were doing so. As a symbol, the cross represents authority, unity, and holiness, and people have used it to invoke good fortune throughout history. It's believed that, in pre-Christian times, people would wish on variations of the cross (such as the Solar Cross) in order to ward off evil. Later, two people would cross each other's fingers (index finger over index finger) after one of them made a wish, and this eventually evolved into one person crossing their fingers on their own. Similar to knocking on wood, crossing your fingers originally meant you wanted God's protection, and not just good luck. Christians would cross their fingers at the mention of any major threat: sickness, Satan, witchcraft, misfortune, and more. It's only with time that the meaning behind the symbol has lost some of its seriousness. For example, 14th century Christians would probably find it a little dramatic that you crossed your fingers to ensure your favorite sports team won. Why we cross our fingers while telling a lie has even murkier origins, but many believe this has to do with God, too. Where crossing your fingers for luck is a way to ask God for protection, crossing your fingers behind your back when you tell a lie could mean you're asking for God's forgiveness. Although crossed fingers are a pretty recognizable gesture, their roots in Christianity help us understand why it isn't a worldwide belief. In fact, crossed fingers are considered an obscene gesture in Vietnam, and other countries have their own "good luck" hand signs. So, the next time you cross your fingers for luck or to signal a lie, remember the gesture's old school roots — and be glad you don't have to ask a nearby stranger to cross fingers with you.