For some unfortunate souls in the Mad Max universe, the term "blood bag" refers to a person of perfect health who is captured by the War Boys and forced to "donate" their blood to a person who has fallen ill.
Overview[]
In Mad Max: Fury Road, Max Rockatansky is overtaken in the Wasteland by a War Party, captured, and brought to The Citadel.
Captives of the War Boys are immediately inspected by the Organic Mechanic and labeled as he must determine what kind of blood the doner has. In Max's case, it is O-Negative, a "high octane" grade, which happens to be the "universal doner." Lucky Max can donate to anyone who needs his blood which makes him a valuable "commodity" to the War Boys -- "blood bag."
Mad Max: Fury Road[]
During the events of Fury Road, Max would fatefully donate to Nux, a top War Boy driver, who was dying from a blood-borne disease. Max was then chained to Nux's car with the IV tube still attached to him much the same way The Humungus chained his victims to the front of his truck in Mad Max 2: The Road Warrior.
Eventually, Max and Nux are crashed during a vicious Wasteland Storm. Soon thereafter, Max breaks free of the chain with a forceful encounter with Imperator Furiosa and Immortan Joe's Five Wives.