Adult Swim, the nighttime version of the Cartoon Network, has been airing a short promo between commercials that states “Adult Swim Is For Conan.” It has also created a tongue-in-cheek spot offering the soon-to-be-ex Tonight Show host a gig.

The pronouncements point to a definitive fault line in the war between O'Brien and Jay Leno for NBC late-night supremacy: It's also a battle between generations, with the geeky, brainy, coddled millennial kids clearly weighing-in for O'Brien. He's an honorary member of gen-y, and “I'm with Coco” has become their battle cry. (See the photos and report of the “I'm with Coco” rally Monday outside Universal Studios, where the show tapes, via LAist. Not much gray hair on display).

Leno's tie-straightening yuks, “Jay Walking” quizzes (which often prey on the young and dumb) and guest appearances by Arnold Schwarzenegger have got nothing on O'Brien's “Masterbating Bear,” Triumph the Insult Comic Dog, and predictions about “The Year 2000” (now changed to 3000) as far as many younger people are concerned. It's cerebral humor for the generation that follows Saturday Night Live's Andy Samberg on YouTube.

And the reason you're not seeing hundreds of people show up in the rain to support Jay Leno is because his fans are your parents, and they're bundling up and complaining about how their joints hurt when it rains.

While Leno was the late-night dominater, NBC could see the writing on the wall in 2004 when it planned the summer, 2009 hand off of The Tonight Show to O'Brien. The network knew viewers would change, and that Leno's audiences were staying the same age. Now its gamble is that seven months of O'Brien's lackluster-but-improving reign at 11:35 was not worth further investment in younger audiences.

Since more and more young viewers are getting their laughs online, NBC could be right. Your parents aren't huddled around the laptop. They'll be there for Leno. But as Samberg has proven, there is synergy between the web and television if you play your cards right. And O'Brien's skits certainly had viral resonance online.

We'll bet one thing: Taking O'Brien away from generation Y viewers will have dire consequences for the future of NBC's already ailing viewership.

Advertising disclosure: We may receive compensation for some of the links in our stories. Thank you for supporting LA Weekly and our advertisers.