Ripped from the Improv Everywhere playbook, this T-Mobile ad by Saatchi & Saatchi's took place at London's Liverpool Street station where 350 dancers amused puzzled commuters with a mixed dance routine. [youtube=http://www.youtube.com/watch?v=VQ3d3KigPQM&fmt=18]
Update: And here's the rehearsal:
[youtube=http://www.youtube.com/watch?v=PxF8i-T9kcg&fmt=18]
[Via]