Cross your fingers for luck.

Combination of having both hands horizontally out at chest level, palms up, fingers spread, elbows close to body and shrug - to mean I don`t know.

Has anybody else ever seen swiping the hand at the neck quickly and repeatedly in a horizontal motion to mean - urgent cut it short or shut up?

Impatience is really conveyed by drumming your fingers.

And where did the wave originate? The sideways flutter like if you are washing your windows wave. Or the same type of hand flutter with your palm towards your body, in an up and down motion to signify "that was a close one."