Jimmy Fallon had Billy Joel as his guest on The Tonight Show earlier this week. Naturally, Fallon decided that the moment presented itself for the two to partake in a duet acapella rendition of "The Lion Sleeps Tonight." Aided by an iPad app called Looper, the two harmonized to create a set of backing vocals, and then launched into a stirring take of the classic song. Obviously with The Roots serving as house band, music has and always will be an important part of The Tonight Show with Fallon as host, but in segments like this, Fallon shows that he has a musical streak of his own. And to be honest, his singing voice is more tolerable than you'd imagine.