Riddle: A prisoner is going to be killed and is told by the executioner that he must make one statement. If his statement is true, then he will be drowned. If his statement is false, then he will be hanged.
What statement can he make to confuse the executioner and not get killed at all?
I will be drowned.
I will be hanged.
I am innocent.
I am guilty.
Answer: I will be hanged is the correct answer.
Then the executioner cannot hang him, or he told the truth and should be drowned. If the executioner drown him, he lied and should be hanged.