'Flash mob' dances for Pope in Rio Hundreds and thousands of people have performed a "flash mob" dance in Rio de Janeiro to celebrate the biggest-ever Roman Catholic World Youth Day. Pope Francis is closing the event with a mass on Brazil's Copacabana beach. Many of the pilgrims had slept on the beach after attending an all-night vigil, which the Pope also led. Sunday's ceremony marks the end of his first foreign trip since becoming pontiff in March.