"No, wait, I change my mind." (CSC)

__TOC__
: "Bruno says 'Go eat sjelkunga berries, scroggly face' to the old man."
: "OK, Bruno, you've just insulted N'gojorogo, the high chief of all the J'garta barbarian tnbes. He is unimpressed by your manners and orders the young chieftain, the one you thought was in charge here, to have you pierced through with poisoned spears."
: "No, wait, that's not what Bruno says... what he really said was..."
Bruno's player seems to have neglected to think about the consequences of his player's actions. He has committed a wrong, and now that he has to pay the price, he wants to recall his action, to make it as if it bad never happened. One can bet that if the DM had said, "the old man quivers in fear and offers you 100 gold coins in tribute" that player wouldn't want to change his mind.
Bruno's player is not alone. The DM will have to deal with the same problem more often than he might like. If the players have been presented with adequate information to make necessary game decisions' they should not be given the opportunity to change their mind once they learn the consequences.
On the other hand., if it is reasonably obvious that a player didn't have all the facts, even though he was paying attention, be lenient and allow the change.
To avoid the situation, try enforcing a policy of "if you say it, you do it." This can be taken so far as to say that anything the player says at the game table that is not a direct conversation with the DM is something that is also said by his character.