I think this is one of the coolest things I have seen. I'm not sure how I would have reacted if I saw this happen in person. If it were a group of 10 people it wouldn't have been a big deal, but to see 200 people across this huge venue, I'm not sure if I would have freaked out or not. This took place back in 2006.
Over 200 Improv Everywhere Agents froze in place at the exact same second for five minutes in the Main Concourse of Grand Central Station. Over 500,000 people rush through Grand Central every day, but today, things slowed down just a bit as commuters and tourists alike stopped to notice what was happening around them.