from an interview here http://www.guardian.co.uk/tv-and-radio/2010/sep/19/jon-hamm-mad-men-don-draper
ON JON HAMM
"He was working as the set dresser on a soft porn film (porn films need set dressers? "You gotta move cameras around, and ashtrays; and continuity is apparently an issue") when Jennifer Westfeldt, who was at that point a distant acquaintance of Hamm’s, invited him to be in a play she was working on in New York. "I came in after another 12-hour day [on the porn film] to this message on my answer phone, and I was so exhausted and depressed and bone tired that I called her back immediately: ‘Yes! I don’t care what it is!’"