If you had a case of the "giggles" at a serious moment, what did you do to stifle them or cover them up ?

Pinch myself or think of something from the past that was embarrassing. I understand because those giggles can happen at a funeral to. It doesn't mean that you think the situation was funny, but those giggles can crop up when you are in a business meeting or in class. All it takes is someone making a funny face or dressed funny.