A keyword or operative phrase that makes it work -- like a light switch.
Look out for the boom. You might even want to duck and cover (yo' ass).
Don your stunna glasses and watch for something mysteriously magical to follow.
Also used as ejaculative exclamation meaning, "lo and behold", "check it out", disappear, bitch! or "it's my birthday". Sometimes accompanied by two snaps of the finger, swinging the hand high left, then right (or any other alternative fancy gesture).
TONY: " I was laying on my bunk reading the Bible, when my celly, Tyrone blurted out, 'NIGGACADABRA !!'. Hellz! Next thing I know I'm bent over, face down and penetrated. Aarrghhhh!! Help me, Momba!"
Li'L PEEPS: "Momma, I want "NIGGACADABRA !!" (breakfast cereal for strong magicians)."