Have someone hold you back, because you’re about to spaz. During his second Desert Trip set last night, Paul McCartney welcomed Rihanna onstage to sing their 2015 single “FourFiveSeconds.” The choice seems somewhat anachronistic considering both the lineup and general tone of the festival, but to be fair, if you’re a Beatles-loving Baby Boomer, the Rihanna song you’re dying to see live is probably “FourFiveSeconds.” Oh, or “Don’t Stop the Music,” but just because that song is a bangin’ good time.