“There were certain things, like, when my wife was pregnant, I didn’t read the baby books, and we got in an argument about it,” the actor explained. He added, “She took it as a hostile gesture, which I totally understand in retrospect.” During their argument, Rudd offered a retort that ended up making it into the movie nearly word-for-word. “I said, ‘What did the cavemen do without ‘What To Expect When You’re Expecting?”” Rudd tells GQ. In the film, much of the plot’s tension comes from Ben’s unwillingness to shape up and put work into his relationship to Alison and their future child. At one point, when she yells at him for not reading baby books, he jokes that Heidi Murkoff’s famous pregnancy guidebook must’ve been carved into the pyramid walls by ancient Egyptians.
“You know, it was funny, and then it’s in the movie now as Seth’s character,” Rudd says. The actor would go on to collaborate with Apatow several more times, and calls their projects together “some of the most fulfilling creative experiences because of the collaboration and because of the freedom that everybody feels [to try new things].” Apatow’s films famously include some great unscripted moments, but Rudd also may just have a knack for good, story-shaping ideas: earlier this week Marvel Studios President Kevin Feige said that it was Rudd who first came up with the idea for Ant-Man to explore the quantum realm.
The Rudd family baby book argument is surely far in the rearview now, but the actor still remembers his wife’s moment of recognition when she first watched “Knocked Up.” He tells GQ, “When my wife and I saw the movie, she’s like, ‘Oh, so, this is an interesting documentary we’re watching right now.'”