Katy Perry and Rihanna Performed at 'Rock in Rio' -- Katy Perry Kisses a Shirtless Guy (Photos/Pictures)

RIO DE JANEIRO, Brazil – Rock in Rio, the world’s biggest music festival kicked off Friday pulling more than 100,000 crazy fans to see their favourite music stars like Rihanna, Katy Perry and Coldplay.

Katy Perry Kisses a Shirtless Guy at 'Rock in Rio'

More than 700,000 people are expected to be part of the week-long event, attracted to see some of the biggest names in pop and rock belting out tunes on Rio de Janeiro’s shoreline.

Katy Perry Kisses a Shirtless Guy at 'Rock in Rio'

On very first day, Rihanna and Katy Perry stole the show with their thrilling performances. Specially Katy Perry when, during her performance, she pulled out one lucky guy from the audience and planted a giant kiss on his cheek! The shirtless guy will probably remember this night forever, and never wash his face again.