From the introduction:
The MC describes the scene and the Danger.
The MC also performs any actions for the Danger, using the actions written on the card as inspiration.
When an Adventurer succeeds at an action, or the MC fails an action, the Danger takes 1 damage.
Whether you are an Adventurer or the Master of Ceremonies, you can't laugh. That is the main rule of the game. You can't laugh.