Add this to the list of ways Jon Hamm is the coolest dude in Hollywood.
The Mad Men star made a surprise appearance at Bonnaroo on Sunday, joining Zach Galifianakis on stage to lead the crowd in a performance of "We Are The World" during the Tennessee festival's annual SuperJam.
WATCH: Jon Hamm Talks Next Moves After Mad Men
Hamm then increased nationwide sales of gummy bears when he fed the treats to Galifianakis in the comedy tent and later to Belle and Sebastian's Stuart Murdoch on stage, because he's Jon Hamm.
Chance the Rapper also made a guest appearance earlier in the weekend -- he joined Kendrick Lamar during Earth, Wind and Fire's set, according to Pitchfork -- and then returned to cover Notorious B.I.G., Will Smith, Montell Jordan and Bell Biv DeVoe during the SuperJam.
Bleachers was on hand with covers as well, with Jack Antonoff singing Bruce Springsteen, Talking Heads and Queen/David Bowie (with SZA), Billboard reports.
PHOTOS: Favorite TV, Movie and Music Reunions
You could tell us the Queen made an appearance at SuperJam, but we're still giving Jon Hamm all the wins here. Because again... he's Jon Hamm. And he fed his friends gummy bears like they are baby birds and basketball hoops.
Hamm did recently say that he's ready to move on from Mad Men (see the video below), but we didn't expect his next big appearance to be at Bonnaroo. We probably should have.