They cross their fingers and spit over their shoulders as charms against the evil eye.
他们交叉手指，往肩后吐口水，以此作为对抗凶眼的符咒。
《柯林斯英汉双解大词典》
2
So, cross your fingers higher interest rates won’t be needed.
所以,祈求好运吧,希望不需要用到较高的利率.
3
You drop an image into a directory with hundreds of other images—let alone hundreds of other files of all types—and you're going to have to cross your fingers.