Heavyweight actors like George Clooney, Mark Wahlberg and Jake Gyllenhaal all flirted with the project, so when it was the literally heavyweight star of "Knocked Up" who was ultimately tapped to bring the iconic Green Hornet to the big screen, it was as if millions of fanboys cried out in terror: "Seth Rogen as Britt Reid? Say what?"

"[The fan reaction] was a little surprising. I love the idea! I think it's going to be a unique and interesting movie," the jocular always-self-deprecating Rogen announced, before adding with a laugh, "but nerds love complaining. You go on [the Web site for] Ain't It Cool News, and everybody complains about everything. They could find out Jesus Christ was making a movie with Frank Miller, and they'd say, 'That's a terrible combination!' "

In all fairness, Frank Miller announcing "Jerusalem: The Real Sin City" might be only slightly more bizarre than Rogen as a costumed super. But, then, his "Green Hornet" will be like no superhero movie we've ever seen before, the 25-year-old star insisted.

"Just a few weeks ago, [co-writer Evan Goldberg and I] laid out our outline for the movie to the studio, and before the phone call, Evan and I were like, 'This is not like any superhero movie — they might just hate that,' " Rogen recalled. " 'It's not using any of the normal superhero movie formats. It's not an origin story. It's more like a regular action movie.' [But] they really liked it and told us to go for it."

So hold onto your green fedoras, Hornet fans! The comedian told MTV News that he's getting buff for his starring role as the flick's titular character. Well, sort of.

"You should believe that I can do some physical activity," Rogen laughed. "You have to believe I can do something."

Getting slim is just one of the ways Rogen is staying true to the action aspects of the character, he asserted. And fans worried about just how well the ferocious talent behind "Superbad" and "Knocked Up" writes action? They should hold off judgment until his next movie hits theaters, Rogen said.

"I think when people see 'Pineapple Express' it will make more sense to them," Rogen teased of his next project, a high-octane action/comedy co-starring James Franco.

But while Rogen and Goldberg are committed to action, the writing duo actually have two outlines for the movie, the actor confessed, similar in some respects but varying greatly in tone.

"There's a more comedic version and a less comedic version, and we don't know what will feel right until we're actually writing it," he revealed to MTV News. "We were about to start writing the script, and then the [writers'] strike hit.

"It's really hard to wrap our head around what the movie will be until we've written the script," he added.

But while Rogen admitted to vacillating between the two versions, he's anything but ambivalent on another tough decision, unabashedly banging the drum for one of two actors to play Kato, the Hornet's Asian manservant and partner in crime.

"I think what's most important about the Kato part is it's someone that you believe can kick the sh-- out of a lot of people," Rogen said of the role made famous by Bruce Lee in the late-'60s television version. "['Kung Fu Hustle' star] Steven Chow is incredible. That was someone we had talked about. I'm a big Tony Jaa fan also."

On the matter of a director, however, Rogen was less committal. "We're always thinking of people who we wouldn't think of. We want guys who will bring something new to the table," he said. "There are two schools of thought: You can get the guy who's a great action-movie director, who's done a million action movies. Or you get the guy who's never done it but has fresh ideas.

"[In the end] we want someone who will make it better than we could have made it," he concluded.