someone who says, "That-there nigger is going to get strung up tonight -- after we burn some crosses in his yard!" has apparently just dropped a big 'ole Atomic N - Bomb!
A Corby-bomb is dropping a shot of Corby's whiskey into a glass of cheap pop (Kroger or Meijer Brand, Vault, ect. ect.) and proceeding to drink/chug it fast.