Hamm's character Ben, who's partnered up with Kristen Wiig's Missy, has reservations about the arrangement and isn't shy about voicing them. Digital Spy sat down with Hamm to discuss working with his real-life partner, playing the asshole and how it's all going to end for Don Draper.
You produced this movie and Jennifer wrote and directed it - is this a more personal movie than any you've done before?
"Yes and no. It's not some deep personal thing that we're bringing to light, but we did have an incredible hand in creating it. That part was really cool. As actors you don't often get an opportunity to really have a hand in creating anything, unless you want to work your ass off. To be fair, that's what we did, especially Jen, having to wear so many hats.
"She was writer, director, actor, sitting in the editing room, going over posters and all of this stuff that's part of producing. From that respect, yes it was a personal thing in that it took up a lot of our day. But I was incredibly proud of Jen's work on this and she did a wonderful job. Her tireless energy and commitment to this project was inspiring."
When you first read the script was Ben the character you were drawn to or did Jennifer say, 'This is who you're going to play'?
"She never said that, which was probably good! 'Honey, I want you to play the horrible, dark asshole.' I wasn't necessarily drawn to it; in fact during several different iterations and versions of it I played Kurt and other people played Ben. When we finally got to actual production it was like, 'Well, I don't think we want to play opposite one another'.
"We are a couple, there is baggage there in the real world. I think it's weird for an audience to say, 'Oh, those people are together in real life'. I don't think people want to see that honestly. It was determined that I should play Ben. And it was great to play opposite Kristen, who I love and is amazing."
Do you always have to like the characters you play?
"No. In fact, the best way to think about characters from an acting standpoint is you don't ever want to judge them. You just play them, it's up to the audience and other people to judge them. Your responsibility is to just tell the truth and just present them as real as possible. Listen, I'm sure your life has several douchebags in it. You know what I mean? We all know people that are maybe not the best people. Life is not filled with you walking around meeting one amazing person after the other. Some people are d**ks. It's not their fault sometimes, sometimes it is, but that's life."
Do you think Don is eventually going to end up content and happy in Mad Men when it's all said and done? Would you like that to happen?
"I don't know, honestly. It's something I think about a lot. I don't know if he knows what content and happy is. There's actually a wonderful line, delivered by a wonderful actress (Elisabeth Moss), where someone says, 'You really don't know when it's good, do you?' And it's true. He has a difficult time with being content. I think that's a hallmark of a lot of successful people, honestly. They're constantly looking for the next thing, which is a shame because you really should enjoy the good times."
You've got The Young Doctor's Notebook with Daniel Radcliffe coming up. Will you be doing an English accent for it?
"I'm going to attempt. We'll see how it works!"
Have you met Daniel yet?
"Yes, I've met Daniel quite a few times. He's a lovely guy and a really, really talented actor. We're really thrilled to do that. It's going to be four episodes on Sky Arts. It's a very, very strange thing. It's an adaptation of a Mikhail Bulgakov series of short stories about his experiences as a young doctor in pre-revolutionary Russia. It's a trip, we've got a really, really talented group of people so hopefully I don't embarrass everyone!"
Friends with Kids opens in UK cinemas on Friday, June 29.