The phrase Double Whammy appears in a current thread. The true / original meaning of this is dark.
As I recall from a TV programme on black American culture, the Whammy is the Evil Eye. You employ it [if you have the 'gift] by widening the eye with index and middle fingers as you stare at the person to be 'whammied' - my word! The Double Whammy employs both hands and eyes, and must only be used if you seek to kill.
So please refrain.