The opposite of plot armor: a predictable guarantee that a character will die for plot purposes.

Refers to the 2006 assassination of Russian defector Alexander Litvinenko in London using polonium, a dangerous and radioactive element.
Andrew: That dude is making out with the main character’s love interest!
Bill: He has plot polonium. He’ll die by two episodes. I’m calling it.
by WeAlsoDoSomeTrolling April 26, 2020
Get the Plot Polonium mug.