This is something that happened spontaneously during the Phillies World Series parade celebration and is not an orchestrated prank, but if it was, it would be awesome. (Though it’s pretty damn cool as it is.)
From the YouTube description:
We snuck out into the middle of Broad Street to snap a pic in front of City Hall and all the crowds. When Will raised his hands for the picture, cheers erupted. So he continued to repeat the gesture, getting wild response from the crowd on both sides of the street up and down the street as far as we could see. We couldn’t have planned this if we practiced and practiced. I wish the video was longer.
via Today’s Big Thing.