The Black Eyed Peas stunned Oprah Winfrey on the opening of the new season of her daytime talk show - by staging the largest single city 'flashmob' dance event ever.

Without the show host's knowledge, Black Eyed Peas star will.i.am teamed up with choreographers to create a dance routine for the band's I Gotta Feeling hit and then called on 800 fans to help him carry out the spectacle on TV.The 800 were taught the moves and then they passed them on to another 20,000 Oprah fans, who showed up for the taping of the TV titan's free block party show in Chicago, Illinois.The amazing finished product aired on TV on Thursday (10Sep09) - when more than 20,000 people took over Chicago's Michigan Avenue and wowed Oprah Winfrey and will.i.am with a colourful synchronised dance routine.After the performance, the singer/rapper told Oprah Winfrey, I didn't think it was going to be this spectacular... You talk about crowd participation, this is beyond... This is incredible.And the host screamed, That is so cool. That is the coolest thing ever... Chicago, I love you.