Under the law of a certain country, anyone caught poaching in the King's forest is punished by hanging or beheading. One day a man was caught poaching in the King's forest. The King allowed the man to make one statement. If the statement was true, he would be beheaded; if it was false he would be hanged.

What statement could the man make to save himself from being killed?

"I shall be hanged."

was the statement made. If the man was to be hanged, the statement he made was true and he should be beheaded. But then the statement he made was false and he should be hanged. Either way the King would have contradicted his own decree.

Statement like

"I am a liar."

could serve the same purpose as long as they are logically inconsistent and the validity of the statement cannot be determined.