Brian

“An official brought the chief rabbi of a town before the Court of the Inquisition and told him, “We will leave the fate of your people to God. I’m putting two slips of paper in this box. On one is written ‘Guilty.’ On the other is written ‘Innocent.’ Draw.” Now this inquisitor was known to seek the slaughter of all the Jews, and he had written “Guilty” on both pieces of paper. The rabbi put his hand inside the box, withdrew a slip of paper—and swallowed it. “What are you doing?” cried the inquisitor. “How will the court know—” “That’s simple,” said the rabbi. “Examine the slip that’s in the box. If it reads ‘Innocent,’ then the paper I swallowed obviously must have read ‘Guilty.’ But if the paper in the box reads ‘Guilty,’ then the one I swallowed must have read ‘Innocent.”
― Leo Rosten, The New Joys of Yiddish: Completely Updated