When you want to wish someone good luck, you'll often tell them, "I'll keep my fingers crossed" that they get the promotion, are pregnant or win the lottery. The gesture is made by crossing your middle finger over your pointer. If you really, really want to wish someone good luck, you might tell them you'll cross all of your fingers and your toes, too. That is, if you live in the U.S., Canada, the U.K. or Australia.
If you happen to be a resident of Vietnam, however, you'll view crossed fingers as a vulgar symbol for female genitalia. Even worse is if another person crosses his fingers just for (or at) you. Then, it's an especially shocking and horrid offense [source: Kruschewsky].
Crossed fingers are an ancient European superstition. Originally, the person locked fingers with another to form a cross (an X, like the Scottish cross of St. Andrew) and wish good luck. Later, the custom devolved to just one person crossing his or her fingers. And now most of the time we don't even cross fingers, but just say we will [source: Panati].