Cigarettes became currency in a WWII POW camp — and obeyed the same laws as real money

Economist R.A. Radford, held in German POW camps during WWII, observed prisoners using cigarettes as money: prices in cigarettes, cigarette-denominated debts, even a makeshift bank issuing IOUs. When Red Cross parcels flooded the camp with cigarettes, prices rose like inflation; when supply dried up, prices fell. He wrote it up as a serious economics paper after the war.

— R. A. Radford, The Economic Organisation of a P.O.W. Camp — Economica, 1945