Last night a mob gathered in Union Square to take part in a fun experiment, put together by Improv Everywhere for the San Francisco Improv Festival.
The Mp3 Experiment instructed attendees to download an mp3 in advance, which they weren't to listen to until told, wear something that was red, blue, yellow or green, and bring an uninflated balloon.
At exactly 6:30pm everyone hit play on their mp3 players and followed the instructions on the track.
Some of the things participants were instructed to do included breathing exercises, square dancing and a big balloon fight.
If you have about 45 minutes to kill, here are some vids of what happened.
