On 'Mad Men,' Jon Hamm is flawed but seemingly invincible. But on the set of his upcoming film 'The Town,' the suave actor is subject to accidents just like everyone else. Hamm was sporting a hole punch-sized crater in his neck during a visit to 'The Late Show with David Letterman' and explained it like so:

"I actually got shot in the neck... Things sort of blow up when you shoot the fake stuff -- a squib blew a piece of Bondo (a rock-hard putty substance) off a car and into my neck. It kinda looks like a zit but it's a way better story." Clip after the jump.