Last month Yahoo! asked me to direct a prank video for their new Start Wearing Purple site. We created a seemingly spontaneous sing-a-long in a Manhattan elevator. As the elevator went down from the 6th floor, a new performer got on at each stop and started singing the same song. We decked out the elevator with hidden cameras and got some great reactions from unsuspecting riders. You can see videos of the other marks as well as behind-the-scenes footage on the Yahoo! site.