During World War II in the Philippines, the occupying Japanese government issued Japanese currency in several denominations. This is known as the Japanese government-issued Philippine fiat peso (see also Japanese invasion money). The Second Philippine Republic under President José P. Laurel outlawed possession of guerrilla currency and declared a monopoly on the issuance of money, so that anyone found to possess guerrilla notes could be arrested or even executed.

Some Filipinos called the fiat peso "Mickey Mouse money." Many survivors of the war [who?] tell stories of going to the market laden with suitcases or "bayóng" (native bags made of woven coconut or buri leaf strips) overflowing with the Japanese-issued bills. According to one witness, 75 "Mickey Mouse" pesos, or about 35 U.S. dollars at that time, could buy one duck egg. In 1944, a box of matches cost more than 100 Mickey Mouse pesos. 

These bills were often used by American psychological warfare personnel as propaganda leaflets. Japanese occupation banknotes were overprinted with the words "The Co-prosperity Sphere: What is it worth?" in an attempt to discredit the Greater East Asia Co-Prosperity Sphere, and dropped from Allied aircraft over the occupied territories.

[ Source - Wikipedia]