Everyone remembers planking! Here are some equally obnoxious/cute/dangerous alternatives to try. Don't forget to take pics!
  1. Corpsing
    Lying like a corpse in places where you might find a corpse (creeks, gullies, allies, etc.)
  2. Reffing
    Go out and get a whistle and referee garb. Penalize strangers for whatever (whistling, talking loudly on phone, swearing at kids, etc.). Deduct yardage accordingly.
  3. How'd I Get Up Here?
    Climb. Remain.
  4. Stealing
    In a store or restaurant, take something with you without paying.
  5. Breaching
    Jumping into conversations you don't belong with profane anecdotes.
  6. Cabbing
    Hopping in the back of a car and giving an address. And just going.
  7. Foresting (requires friends)
    Create an urban forest of people, all standing motionless together.
  8. Magikarping
    If nautical nonsense be something you wish.