COMMON If you keep your fingers crossed or cross your fingers, you hope for luck or success in something. I'll be keeping my fingers crossed that everything goes well. We all cross our fingers and hope it never happens. But if long-term illness struck tomorrow, could you keep paying the bills? Note: People say fingers crossed when they are wishing someone good luck or hoping for good luck for themselves. We don't have tickets but we're going anyway. Fingers crossed we'll be able to get in. Note: People sometimes actually cross their middle finger over their index finger when they use this expression or are wishing someone good luck. In the past, people believed that making the sign of the cross in this way was a way of protecting themselves from the devil or bad luck.