Alright kiddo, you know how sometimes you make a wish and you cross your fingers hoping that it comes true? Well, crossing your fingers is also used in other situations, like when you're afraid of getting in trouble or when you want something to go your way.
When you cross your fingers, you take your pointer finger and your middle finger and put them on top of each other, like you're making an X. This is supposed to bring good luck, or help you avoid something bad from happening.
Some people also use crossed fingers to show that they're not telling the truth. It's like a secret signal between friends that means "I'm lying but don't tell anyone." But remember kiddo, it's always better to be truthful and honest with yourself and others.