Bill Hader and Seth Rogan in Superbad Melissa Moseley/Courtesy of Columbia Pictures

During the interim, Rogen would move to Los Angeles and be discovered by Apatow when the latter was casting his high school–set TV show, Freaks and Geeks. Although Freaks was cancelled, Rogen would remain on Apatow's crew list, serving as a writer and cast member on the TV show Undeclared and then jumping to the big screen alongside Apatow with The 40-Year-Old Virgin. The success of the Steve Carell comedy not only opened the door to Rogen becoming a leading man in his own right, with Knocked Up, but the R-rated comedy paved the way for Rogen and Goldberg's pet project.

"It was always basically about two guys who were trying to get alcohol for the girls they liked," Rogen says of Superbad. "That was always there, but there really was no emotional story to it. Judd really helped develop that."

Yet as Apatow was able to put the script into production, Rogen became too old to play "Seth," the randy high school senior whose more studious best friend "Evan" is on the verge of leaving for college without him. Greg Mottola, the film's director, didn't have to look far for Evan, casting Cera, with whom he had worked on Arrested Development, but finding Seth proved harder.

"I was a bit of a stickler about age because I wanted the characters to all be like 19," Mottola says. "We read a ton of people and no one was good at it. No one could make that character sympathetic."

Rogen admits that casting Cera first was a case of "good and bad": "It was bad because Evan wasn't even the funny guy. We were like, 'shit, the non-funny guy's funnier than the funny guy is.'"

Apatow was in the midst of filming Knocked Up when he spotted Hill sitting with Rogen and costar Bill Hader (who, incidentally, would end up partnering with Rogen in Superbad as the cops who follow Evan and Seth's wild night). After Apatow asked how young the 24-year-old Hill thought he could play, Hill went inside Rogen's trailer to shave and shoot an audition tape. Suddenly, Cera's Martin had his Lewis.

Christopher Mintz-Plasse, Jonah Hill, and Michael Cera in Superbad Melissa Moseley/Courtesy of Columbia Pictures

The two would become fast friends over sushi and nightly drives — Cera, now 19, wasn't driving yet, so Hill would pick him up at his hotel and the two would share their love of films and music and even had a mutual friend in common. The pair was joined by Christopher Mintz-Plasse, a newcomer who is easily Superbad's biggest revelation as the gangsta-gabbing McLovin (the name being a result of a botched fake ID). Onscreen and off, the trio now share an effortless chemistry that makes it seem as though they've known each other as long as the real Seth and Evan. Just as the dialogue in Superbad feels honest because of how old Rogen and Goldberg were when they wrote their first draft, the trio convey a sincerity that is uncommon among actors. When the subject of Apatow's next production arises in conversation — the John C. Reilly musical parody Walk Hard, in which Hill has a cameo as Reilly's deceased brother — there isn't any hesitation. A sample of the conversation: