Featuring Rihanna, Nicki Minaj, Calvin Harris, Jessie J and more

US Singer Rihanna performs during a concert in Oslo on June 29, 2012. AFP PHOTO / SCANPIX NORWAY / Erlend Aas ***NORWAY OUT*** (Photo credit should read AAS, ERLEND/AFP/GettyImages)

Featuring Rihanna, Nicki Minaj, Calvin Harris, Jessie J and more

LONDON, ENGLAND - JULY 08: Rihanna performs at Barclaycard Wireless Festival at Hyde Park on July 8, 2012 in London, England. (Photo by Danny Martindale/Getty Images)

Featuring Rihanna, Nicki Minaj, Calvin Harris, Jessie J and more

LONDON, ENGLAND - JULY 08: Rihanna performs at Barclaycard Wireless Festival at Hyde Park on July 8, 2012 in London, England. (Photo by Danny Martindale/Getty Images)

Featuring Rihanna, Nicki Minaj, Calvin Harris, Jessie J and more

LONDON, ENGLAND - JULY 08: Rihanna performs at Barclaycard Wireless Festival at Hyde Park on July 8, 2012 in London, England. (Photo by Danny Martindale/Getty Images)

Featuring Rihanna, Nicki Minaj, Calvin Harris, Jessie J and more

LONDON, ENGLAND - JULY 08: Rihanna performs at Barclaycard Wireless Festival at Hyde Park on July 8, 2012 in London, England. (Photo by Danny Martindale/Getty Images)

Featuring Rihanna, Nicki Minaj, Calvin Harris, Jessie J and more

LONDON, ENGLAND - JULY 08: Rihanna performs at Barclaycard Wireless Festival at Hyde Park on July 8, 2012 in London, England. (Photo by Danny Martindale/Getty Images)

Featuring Rihanna, Nicki Minaj, Calvin Harris, Jessie J and more

LONDON, ENGLAND - JULY 08: Calvin Harris performs at Barclaycard Wireless Festival at Hyde Park on July 8, 2012 in London, England. (Photo by Danny Martindale/Getty Images)

Featuring Rihanna, Nicki Minaj, Calvin Harris, Jessie J and more

LONDON, ENGLAND - JULY 08: Calvin Harris performs at Barclaycard Wireless Festival at Hyde Park on July 8, 2012 in London, England. (Photo by Danny Martindale/Getty Images)

Featuring Rihanna, Nicki Minaj, Calvin Harris, Jessie J and more

LONDON, ENGLAND - JULY 08: Calvin Harris performs at Barclaycard Wireless Festival at Hyde Park on July 8, 2012 in London, England. (Photo by Danny Martindale/Getty Images)

Featuring Rihanna, Nicki Minaj, Calvin Harris, Jessie J and more

LONDON, ENGLAND - JULY 08: Calvin Harris performs at Barclaycard Wireless Festival at Hyde Park on July 8, 2012 in London, England. (Photo by Danny Martindale/Getty Images)

Featuring Rihanna, Nicki Minaj, Calvin Harris, Jessie J and more

LONDON, ENGLAND - JULY 07: Nicki Minaj performs at Barclaycard Wireless Festival at Hyde Park on July 7, 2012 in London, England. (Photo by Danny Martindale/Getty Images)

Featuring Rihanna, Nicki Minaj, Calvin Harris, Jessie J and more

LONDON, ENGLAND - JULY 07: Nicki Minaj performs at Barclaycard Wireless Festival at Hyde Park on July 7, 2012 in London, England. (Photo by Danny Martindale/Getty Images)

Featuring Rihanna, Nicki Minaj, Calvin Harris, Jessie J and more

LONDON, ENGLAND - JULY 07: Nicki Minaj performs at Barclaycard Wireless Festival at Hyde Park on July 7, 2012 in London, England. (Photo by Danny Martindale/Getty Images)

Featuring Rihanna, Nicki Minaj, Calvin Harris, Jessie J and more

LONDON, ENGLAND - JULY 08: Jessie J performs at Barclaycard Wireless Festival at Hyde Park on July 8, 2012 in London, England. (Photo by Danny Martindale/Getty Images)

Featuring Rihanna, Nicki Minaj, Calvin Harris, Jessie J and more

LONDON, ENGLAND - JULY 08: Jessie J performs at Barclaycard Wireless Festival at Hyde Park on July 8, 2012 in London, England. (Photo by Danny Martindale/Getty Images)

Featuring Rihanna, Nicki Minaj, Calvin Harris, Jessie J and more

LONDON, ENGLAND - JULY 08: Jessie J performs at Barclaycard Wireless Festival at Hyde Park on July 8, 2012 in London, England. (Photo by Danny Martindale/Getty Images)

Featuring Rihanna, Nicki Minaj, Calvin Harris, Jessie J and more

LONDON, ENGLAND - JULY 07: Rita Ora attends at Barclaycard Wireless Festival at Hyde Park on July 7, 2012 in London, England. (Photo by Danny Martindale/Getty Images)

Featuring Rihanna, Nicki Minaj, Calvin Harris, Jessie J and more

LONDON, ENGLAND - JULY 08: Rihanna performs at Barclaycard Wireless Festival at Hyde Park on July 8, 2012 in London, England. (Photo by Danny Martindale/Getty Images)

Featuring Rihanna, Nicki Minaj, Calvin Harris, Jessie J and more

LONDON, ENGLAND - JULY 07: Rita Ora performs at Barclaycard Wireless Festival at Hyde Park on July 7, 2012 in London, England. (Photo by Danny Martindale/Getty Images)

Featuring Rihanna, Nicki Minaj, Calvin Harris, Jessie J and more

LONDON, ENGLAND - JULY 07: Rita Ora performs at Barclaycard Wireless Festival at Hyde Park on July 7, 2012 in London, England. (Photo by Danny Martindale/Getty Images)

Featuring Rihanna, Nicki Minaj, Calvin Harris, Jessie J and more

LONDON, ENGLAND - JULY 07: Rita Ora performs at Barclaycard Wireless Festival at Hyde Park on July 7, 2012 in London, England. (Photo by Danny Martindale/Getty Images)

Featuring Rihanna, Nicki Minaj, Calvin Harris, Jessie J and more

LONDON, ENGLAND - JULY 07: Rita Ora performs at Barclaycard Wireless Festival at Hyde Park on July 7, 2012 in London, England. (Photo by Danny Martindale/Getty Images)