A loveable fixture in Apatow projects since Freaks And Geeks, Seth Rogen is a revelation as a stoned slacker who lucks into a one-night stand, but struggles to deal with the complications that follow. Perpetually between jobs, Rogen and his housemates (Jay Baruchel, Jonah Hill, Martin Starr, and Jason Segel—all brilliant Apatow discoveries) are trying to launch a celebrity skin website called fleshofthestars.com, but they smoke weed and clown around most of the day. With a little charm and a lot of alcohol, that great equalizer, Rogen manages to seduce Katherine Heigl, a gorgeous career-minded woman who's well out of his league. When Heigl discovers that she's pregnant, she gets back in touch with Rogen and they have to figure out how to make their relationship—as mother and father, and possibly as boyfriend and girlfriend—work. Paul Rudd and Leslie Mann lend invaluable support as Heigl's brother-in-law and sister, who know a lot about the stress of child-rearing and long-term partnerships.
Knocked Up goes through every step of the pregnancy—without skimping on the gynecological details—and watches as the baby develops, along with Rogen and Heigl's relationship. Naturally, there's some confusion between the two: Just because they want to do the responsible thing as parents, does that make this odd couple right for each other? Apatow and company take these matters seriously, yet most of the scenes are played for laughs, too, and they mine a wealth of great material. No one writes for ensembles better than Apatow (who could probably spin whole movies out of the misadventures of Rogen's buddies or Rudd and Mann's contentious marriage), and his players are all skilled at giving his work a loose, improvisational feel. That looseness again results in a comedy that stretches well past the two-hour mark, but that's part of the Apatow touch: He makes viewers want to hang out with his characters indefinitely.