Florence Welch helps Jimmy Fallon belt out 'Balls in Your Mouth' By Rolling Stone While they're currently trekking across the U.S., Florence and the Machine swung by "Late Night With Jimmy Fallon" last night for a very special performance. The band performed "Spectrum (Say My Name) " to close out the show, but the real highlight came earlier, when Florence Welch joined Fallon for a rousing rendition of "Balls in Your Mouth" -- the protest song he wrote in 2010 about the tar balls washing up on the shore following the BP oil spill. As Hurricane Isaac has caused old tar balls to reach shores again, it was an apt opportunity to bring back the track, and Welch gave the song's earworm of a refrain -- "Balls in your mouth / Balls in your mouth / Don't swim in the ocean / You'll get balls in your mouth" -- a full diva makeover. The studio audience and the Roots made sure to get in on the fun, too.