During Oprah Winfrey's kickoff show that aired on September 10, 2009, thousands of people joined in to perform a flash mob dance. As many as 21,000 people along Chicago's Michigan Avenue participated in the synchronized crowd dance as the Black Eyed Peas sang their hit song "I Got a Feeling." A flash mob is a group of people who join together to perform some sort of unusual stunt - including a dance.http://www.nbcchicago.com/around-town/events/Oprahs-Flash-Mob-Style-Dance-58166602.html
Flash Mob Dance on Oprah
Flash Mob Dance Party to Black Eyed Peas' "I Gotta Feeling" on Oprah Winfrey Festival Chicago 2009