'Step Brothers' set was so riotous, Mary Steenburgen had 'to think of the saddest things I could to keep from dying laughing at these idiots'

Mary Steenburgen is only 14 years older than Will Ferrell, which is wild when you realize she has twice mothered the comedy star in a movie. The first time came in the 2003 contemporary Christmas classic Elf, where Steenburgen played Ferrell’s stepmom, which made sense in terms of the story. (Also, this is a movie in which a 6-foot-3 human is raised among elves in the North Pole, so pretty much anything goes.)

But by the time Step Brothers rolled around five years later, Ferrell felt he needed permission to ask the Oscar-winning actress to play his birth mother.

“He called me and said, ‘Would you be offended if I asked you to actually play my mom?,’” Steenburgen told Yahoo in a recent Role Recall interview. “I said, ‘No, I would be offended if you asked someone else.’”

Released in theaters 15 years ago, on July 25, 2008, Step Brothers would become another instant comedy classic for the Saturday Night Live alum. Directed by Adam McKay from a script he cowrote with Ferrell, the laugh-out-loud romp paired Ferrell with John C. Reilly as two fully grown, developmentally arrested men forced to live together following the marriage of their respective parents (Steenburgen and Richard Jenkins). “People come up to me every day about that movie,” Reilly once told us. “For a big, broad comedy, people found a lot of common ground in that movie.”

Steenburgen, 70, was a protégé of Jack Nicholson’s, won an Oscar for Melvin and Howard, met husband Ted Danson on the set of Pontiac Moon and has appeared in such other screen favorites as Time After Time, Parenthood, Back to the Future III and Philadelphia. But she calls Step Brothers “one of the apex moments” of her life.

“It was just one of those things that you can’t believe how lucky you are,” she says. “And Richard Jenkins, who I love, we looked at each other on the first day and went, ‘We’re working with these two comedic geniuses who literally can’t say anything that isn’t going to break me, a terrible giggler, up.’ And we were like, ‘What are we doing here?’ And then I said, ‘You know what? We've got to make people believe that these two idiots do live home with their parents. And we’re just the dysfunctional parents that would still have middle-aged people at home like this. And honestly, it was just a total joy.”

The laughs were so infectious that Steenburgen said the production eventually gained a live studio audience.

“[Usually] people come to film sets and they think they’re going to love it, and then they watch it for five minutes and they get bored and they leave,” she says.

“But on this film, people would come bring their lawn chairs, go sit by Adam McKay, who we had to keep so far away from us because he was laughing so loudly. He was so far from us, he had to have a megaphone. And every day there were more and more people, it was like doing theater, you know?

“My job was to think of the saddest things I could think of all day long to keep from dying laughing at these idiots that were doing this stuff. It was just beyond hysterical. And half of that film was improvised. So you never knew what was coming out. You couldn’t prepare in the morning. It was so amazing.”

Editor's note: The interviews for this story were conducted before the Hollywood actors strike.