In 1925, small-time criminal Alves Reis convinced the British firm that printed Portuguese currency to make some for him, and he passed some 5 million phony escudos into the Portuguese economy. Because the unauthorized bills came from official presses, the government at first could detect nothing wrong, but finally it found some duplicate serial numbers in Reis’ accounts and the game was up.

Reis argued that he had cheated no one, but he was sentenced to 20 years in prison. Lord Macmillan of Aberfeldy called the scheme “a crime for which, in the ingenuity and audacity of its conception, it would be difficult to find a parallel.”

And it raises an interesting legal question: If currency is produced by an official government printer, can it still be called counterfeit?