Toward the end of Phoenix's crowd-pleasing set, out strolled none other than R&B mega-star R. Kelly, wearing a bejeweled baseball cap and motocross gear, to sing his hits "Ignition (Remix)" and "I'm a Flirt" over the band performing the melody of their own hit, 2008 single "1901″ and new song "Chloroform."

While some in the crowd seemed legitimately confused at what was occurring onstage in front of them, a majority of the masses gathered for Phoenix's set were excited by the surprise pairing, lustily singing along to R. Kelly's lyrics.