What a way to slow down...and enjoy life. Drop out of the rat race. Take a breath. Stop and smell the roses... You think of the metaphor, but "Flash Mobs" are an intriguing phenomenon to demonstrate unified action in public places. Here's an intriguing example...
What a great, simple way to get a group to demonstrate... well... almost anything.
Point to something.
Lift arms in wonder...
What can you think of for a public moment of silence or demonstration?
This could have great tie-ins for a book. For a cause. For a group of any kind. Bring a specific item and hold it up. Do a dance.
The keys are a large group. And a public place. For a moment in time.