Control - You must learn control!
Some GM/DM/ST Advice:
There are times when you are running a game, and you set up the great encounter facing the big bad evil guy and the guy is about to spill the beans on his master plans. Cliché to the max but it happens. Ok there is always one smart ass player that will want to shoot him before he is done. As a rule of thumb just ask to not attack until after the monolog. This will solve a lot of issues.