Improv Everywhere

[Not Afraid]

I don't think it would be too difficult to pull off a similar stunt locally. I've done similar things with groups in the past. (Ever stood in a crowd and looked and pointed at "nothing" to get evveryone to do the same thing?) It just take a bit of organization and communication. The trick is to find something just obvious enough to be fun and noticable but not terrible enough to be illegal.