I came across this the other day and couldn’t pass up on posting it. It is just too awesome.
This group in New York called Improv Everywhere is pretty well known for staging large scale public pranks. Some have a negative connotation on pranks, but these are more like friendly fun stunts.
Click the “more” link for other pranks.
They are the ones that staged the Grand Central Station Freeze in New York City, where 207 “agents” froze at the exact same time in the middle of Grand Central Station for 5 minutes.