Cross your fingers
Those wishing for luck will often cross one finger over another, a gesture that's said to date back to early Christianity. The story goes that two people used to cross index fingers when making a wish, a symbol of support from a friend to the person making the wish. (Anything associated with the shape of the Christian cross was thought to be good luck.) The tradition gradually became something people could do on their own; these days, just saying "fingers crossed" is enough to get the message, well, across.something that is slightly dangerous in the first place.