Having a person blackmail a person when that person is already blackmailing a person. similar to inception only instead of dreams its blackmail.
1. Person A gets blackmailed by person B, person B gets blackmailed by person C, and person D blackmails Person C, and so forth and so on.
2. wow that's a really long line of blackmail, it kinda hurts my brain like inception did. Hey lets call it Blackception.