If you have a dumb comedy idea, give it to Jon Hamm. That dude is game, every time. On Wednesday night’s The Tonight Show Starring Jimmy Fallon, Hamm joined Fallon on a deeply odd bit. The premise is this: Before they were famous, Hamm and Fallon were in a roots rock-lookin’ band named Burlap. They dressed like Jim Carrey that one time at the MTV Movie Awards. (Remember that?) But their songs are sort of vocal jazz. It’s a chance for dumb wigs, dumb song lyrics, and for Jon Hamm to make some really weird faces at the camera. Not since playing JFK in one of Bill Hader’s “Vincent Price Halloween Special” sketches has Hamm looked this goofily at a camera.