Katy Perry has teamed up with Rebecca Black for Perry's Lifetimes tour. Black, who appeared in Perry's 2011 video for Last Friday Night, was at the Los Angeles stop on her own Salvation tour on the weekend when Perry joined her for a rendition of that song.

In a performance that got social media buzzing, Katy Perry and Rebecca Black teamed up for a surprise duet of viral hit "Last Friday Night (T.G.I.F.)" at Rebecca Black's Los Angeles concert last night.

S howbiz has always granted fans a front-row seat to artists’ dramatic highs and gut-wrenching lows. But when the fall is too steep, reality becomes a bitter pill to swallow. Th