The act of denying a duty or responsibility,thus leaving it to others. When one calls "no whammy", on something, he/she is refusing to take responsibility for it. The last person in the group to call "no whammy" is he/she whom,by default, takes responsibility of the proposed issue or action.
"No Whammy on sitting next to Jacob!"
"No Whammy on driving!"
"Hey,I called No Whammy on the aisle seat so you have to sit there!"
(four girls in a bikini with big tits walks into Rob's house and he is pure and loves god)
Rob: oh shit OH GOD FUCK NO WAIT FUCK GOD NO AHH HELP IM GONNA GET FUCKING RAPED HELP FUCK NO PLEASE HELP NO, NO, NOOO- (Rob breaks out of his bedroom's window and escapes the hoeslut thot girls)