The Keeping Up With the Joneses co-stars helped to kick off the Superjam dance party and led the crowd in a rendition of the 1980s hit “We Are the World.”
Watch the video from a concert-goer below!
Meanwhile, Jon and Zach also performed a surprise comedy set at the festival that day.
15+ pictures inside of Jon Hamm and Zach Galifianakis at Bonnaroo… More Here! »