Laugh, and the whole world laughs with you: Except for when they just stare at you with disdain.
I had never heard of Dane Cook until this week, and I started listening to some of his routines while at work. With my headphones on, I did that sort of lean-forward-and-don't-breathe laughing that makes people think, "Man, she must be listening to something really hysterically funny." And I was! Or so I thought.
My boss pulled up the "Car Alarm" routine (clip at lower left on this page: http://www.npr.org/templates/story/story.php?storyId=5034153). I started laughing again involuntarily. As I laughed and laughed and the routine continued to play, I slowly realized that no one in the room was amused. They were all just looking at me, like, I can't believe you think this is that funny.
I guess it serves me right for every apathetic stare I've given to Monty Python fans.