That all changed with the debut of “Space Ghost: Coast to Coast” in 1994. “SGC2C,” as its fans call it, was a slice of grown-up fun. Space Ghost himself had been the star of his own straight-forward Hanna-Barbera cartoon a generation ago. But this time around, the animators gave him a David Letterman-style talk show to host. On every episode, he would try in vain to conduct intelligent interviews with celebrities as diverse as Jerry Springer, Sarah Jessica Parker and Radiohead’s Thom Yorke. He always collapsed under the weight of his own vapid banter. And of course, most viewers of the Cartoon Network loved it and for the better part of a decade, “SGC2C” existed all by his lonesome.

Then last fall, the network introduced “Adult Swim,” a block of programming on Sunday nights that contained four new cartoons–all in the “SGC2C” mold. They’re funny, they’re bizarre, and they all make terrific use of the tens of cartoon characters in the HB canon.

Like “SGC2C,” the four new cartoons are–by financial necessity–a hybrid of the genre’s high and low traditions. They’re 12 minutes long, like the classic WB and MGM ’toons that ran in front of movies in the 40’s and 50’s. But their animation style is more like the Hanna-Barbera stuff of the ’60s, ’70s and ’80s–totally schlocky. All contain the same quick-witted humor that makes “SGC2C” so sensational. The laughs come out of absurd dialogue, good timing–and great editing. Here’s a walk through the block:

The hottest show among them is “Harvey Birdman, Attorney at Law” (11:30 p.m. Sundays), in which the title character–once the star of the 1960s HB show “Birdman”–is an ignoramus lawyer whose clients are all HB characters. In one episode, Harvey helps “Jonny Quest” star Dr. Benton Quest and his “traveling companion” Race Bannon settle a custody battle over young Jonny.

The show is a boon for Saturday morning nostalgics: not only do the series’ writers seem to have watched every HB show ever created, but the animators have also copied the styles of the original artists to eerie effect. Fred Flintstone has his characteristic thick lines and the “Jonny Quest” characters retain their trademark shading.

It’s another sign of the creators’ affection for HB characters that when Shaggy and Scooby-Doo are charged with “possession,” both are exonerated–and the substance they were accused of handling never revealed. Of course, not all HB characters are as revered. The animators have allowed Quick Draw McGraw to be beheaded and Scrappy-Doo to be carried off by a hawk.

“Sealab 2021” (11:45 PM) is the closest to perfection in its plotless simplicity. “Sealab 2020” was HB’s first environmentalist cartoon (it debuted in 1972), and it’s a work of some deviance to update such a benign show and basically tear it apart. “Sealab 2021’s” best episodes show the crew of the titular underwater research center debating themselves into a crescendo of sadistic, innuendo-filled idiocy. (“You better believe I’d put my brain in a robot’s body.” “Robot body? No way! That goes against the natural order!” “You’d have the strength of five men!” “I got that now.” “But since you’re that strong, if you tried to pet a kitten, you’d crush them.” “Oh no! Poor kitty!”) Most shows end with the implosion of Sealab and the apparent death of everyone aboard. Catastrophe has rarely been so funny.

“Aqua Teen Hunger Force” (12:00 AM) is drawn by the same team who created “SGC2C.” The show chronicles the daily life of – ready? – a talking Extra Value Meal. Yep–you read correctly. The characters are named Master Shake, Frylock and Meatwad. The three of them solve mysteries from their house in suburban New Jersey.

“ATHF” takes “less is more” to the furthest extreme: The cartoon never explains why these foods are actually alive and speaking English. Nor do we ever learn why they’ve chosen to become detectives, or why they’re even called the Aqua Teen Hunger Force. It’s the most incoherent of the four new programs. The most consistent character: Carl, the team’s Jersey-accented neighbor, who always wears a wife-beater. Most episodes follow a simple pattern: Carl’s property gets abused, Carl becomes hilariously unhinged, Carl gets put in his place by the Aqua Teens or some other villain.

Last comes “The Brak Show” (12:15 AM). The cartoon centers on the home life of Brak, a longtime favorite of “Space Ghost” watchers, mostly for his voice. It’s hard to describe, but here’s a stab: imagine a Muppet whose mother was a habitual crack user.

Brak lives in bizarre, “Leave It to Beaver”-style suburbia. Simple-minded and benevolent, he remains ignorant of the insults from his own father and from his best friend. (Brak: “Hey Zorak, guess what I’m going to be at the talent show this year?” Zorak: “A loser.” Brak: “Ehh! Wrong!”). Episodes get half their mileage out of Brak’s habit of breaking into song.

It’s basically plotless. But viewers don’t seem to care. Why would they? They’re sitting in front of the TV, eating something sweet, taking in something silly. It’s like they’re seven years old again. And for one measily hour at the end of the weekend, would that be so bad?