The only rule is that you can't participate if you're a real time traveler. This is just a game for us normals. Some suggestions on what to do:

- Greet people by referring to things that don’t yet exist or haven’t existed for a long time. Example: "Have you penetrated the atmosphere lately?" "What spectrum will today’s broadcast be in?" and "Your king must be a kindly soul!" [...]

- Walk up to random people and say "WHAT YEAR IS THIS?" and when they tell you, get quiet and then say "Then there’s still time!" and run off.

- Stand in front of a statue (any statue, really), fall to your knees, and yell "NOOOOOOOOO" [...]

- Airplanes are terrifying.  Also, carry on conversations with televisions for a while.

Link -via Glenn Reynolds | Image: NBC