The King's Adviser

A king decides he is going to fire one of his advisers. He tells him that he has written "You're fired" on one slip of paper, and "You can stay" on another, and that the adviser is to choose one at random. The king has secretly written "You're fired" on both notes, but unbeknownst to the king, the adviser has found this out! How can the adviser keep his job without telling the king that he knows both notes are the same?

The adviser can select either one of the notes, then destroy it by throwing it in the fire (or by eating it, if there is no convenient fire nearby). He can then tell the king to open the other note, and deduce by elimination which was the one selected. Since the remaining note is guaranteed to say "You're fired," the king must pretend that the note the adviser selected said "You can stay."