Just like in Katy Perry's music video for "Last Friday Night", Rebecca Black appeared at Perry's concert unannounced. Perry was entertaining a sold-out show at L.A's Nokia Theater on Friday, August 5 when Black suddenly emerged from the backstage to help Perry finish the cover of her "Friday" song.
The venue was filled to the brim, mostly with women. Perry belted out a mixture of her hits such as "I Kissed a Girl" and "Teenage Dream" at the beginning of her set and began covering other artists' songs toward the middle. She sang Rihanna's "Only Girl (In the World)", Willow Smith's "Whip My Hair" and did a snippet of Jay-Z's "Big Pimpin".
While the acoustic set was still on stage, Perry led the crowd to sing Black's "Friday" and surprised them with the original singer. Black, who made a cameo in the music video of Perry's aptly titled song "Last Friday Night", sat on a stool and finished the song as a duet.
Perry closed her performance with another cover, this time Whitney Houston's "I Wanna Dance With Somebody", and "Firework".