Someone at ABC probably feels pretty stupid. Instead of fooling around with Bill Maher and Jimmy Kimmel in an attempt to win audience share from Leno and Letterman, all ABC needed to do was air a few old cartoons. Who knew?

Cartoons for adults and teens are all the rage.

Since expanding in January to five nights a week, Cartoon Network's late-night block of cartoons, Adult Swim, has seen its audience balloon, especially in the advertiser-friendly 18-34 demographic, which has increased 138 percent. And Adult Swim is beating "Jimmy Kimmel Live," "Last Call with Carson Daily" and "The Late, Late Show with Craig Kilborn" among what should be those shows' core audience — young men. Obviously, college-age guys love cartoons.

Adult Swim has benefited greatly from bonehead decisions at other networks. Its two most popular programs are rejects from Fox's prime-time line-up: "Futurama" (from "The Simpsons" creator Matt Groening) and "Family Guy." Both shows were solid performers for Fox, especially "Family Guy" while it was paired with "The Simpsons" on Sunday nights. But for various reasons, Fox set out to sabotage both. "Futurama" suffered from a lack of promotion, while "Family Guy" moved from one dead-end timeslot to another.

Perhaps Fox would have had a clue had it released "Futurama" and "Family Guy" to DVD sooner. The four-disc season 1 and 2 set of "Family Guy" sold 400,000 copies in its first month of release.

The rest of the Adult Swim line-up, made up mostly of anime action series and Cartoon Network original programming, is doing well, too.

Cartoon Network recently inked a deal to have Hot Topic, a store catering to teenage goths and other assorted mallrats, carry exclusive Adult Swim merchandise.

This is where another channel blew it. Nickelodeon had a respectable hit on its hands with "Invader Zim." Like Adult Swim, "Zim" led to profitable merchandising opportunities with Hot Topic. But the executives at Nickelodeon didn't understand "Invader Zim"and pulled the plug. Without the show, the market for "Invader Zim" clothing, trinkets and plush toys evaporated.

In the old days, folks usually waited until the toys stopped selling before killing the cartoon that sold them.

Now, Nickelodeon's parent company, Viacom, is trying again, this time with a block of edgy, "adult" animation on TNN, soon to be rechristened Spike TV. The shows — "Stripperella," "Gary the Rat" and the new "Ren and Stimpy" — are terrible. But the initial ratings are good, again especially among men 18-34.

Maybe if Nickelodeon hadn't fired the "Invader Zim" animators and alienated the show's creator, Jhonen Vasquez, the show could find a new home on Spike, which could use a little class. And you'd think someone at Viacom would notice all of the bootleg "Invader Zim" DVDs floating around the Internet and try to cash in with a legitimate release. But no. If the DVDs sold well, someone would have to admit that canceling the show was a stupid idea.

Meanwhile, at Cartoon Network wiser heads prevail. Two of the network's original programs, "Space Ghost Coast to Coast" and "Aqua Teen Hunger Force," are coming to DVD on Nov. 18, with each getting a 2-disc, 16-episode release, complete with extras like creator commentaries, music videos and bonus footage. Each set will retail for $29.98.

Other Adult Swim originals, like "Sealab 2021," "The Brak Show" and "Harvey Birdman: Attorney at Law," will follow.

I bet Cartoon Network makes a mint.