[bng101]

I have seen it done in both live and tourny play.

From what I understand of the rules is this:
You can lie about your hand, but can not tell the truth about what you have.(don't know about after the allin stuff). And, if your hand touches the muck, then your hand is dead.

I have ask this person about it. His reply is this "it's my job to win the pot anyway possible and it's his job to make sure his hand is dead, before throwing it away"