You Have To Open Wider For Jon Hamm! Watch The Mad Men Star Throw Gummi Bears Into Jimmy Kimmel's Mouth!

Jon Hamm always seemed so serious and grown-up on Mad Men, but it turns out he was just a big kid the whole time!
Now that he’s filming a movie with Zach Galifianakis, he’s just being completely silly — and he’s good at it!
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The two apparently developed a kind of sideshow act where Jon throws Gummi Bears into Zach’s mouth on set; and they’re so good at it they even performed at Bonnaroo!
Of course, when Jon told Jimmy Kimmel about it on Tuesday night’s show, the host just had to get in on the action himself!