Two men came before Nasrudin when he was magistrate.  The first man
said, "This man has bitten my ear -- I demand compensation."  The
second man said, "He bit it himself."  Nasrudin withdrew to his
chambers, and spent an hour trying to bite his own ear.  He succeeded
only in falling over and bruising his forehead.  Returning to the
courtroom, Nasrudin pronounced, "Examine the man whose ear was bitten.
If his forehead is bruised, he did it himself and the case is
dismissed.  If his forehead is not bruised, the other man did it and
must pay three silver pieces."