“Mad,” as you can guess from the rifle, is based on the format of Mad magazine: tasteless juvenile satire for adolescents of all ages. The first show opens at “Fox World Headquarters,” a men’s room where a couple of slimy programming execs are trying to convince their boss how great this new show’s gonna be. “We’ve got publicity going full throttle, sir,” says Slimy Exec 1. “How about merchandising?” the boss barks from inside a stall. Slimy Exec 2 chimes in: “We have everything from Alfred E. Neuman’ beer hats to ‘What me worry?’ sports bras.” (Picture “SNL” executive producer/merchandise-monger Lorne Michaels seeing this and wondering, “Why didn’t I think of that?”) The only problem is the cast. They don’t have one. So the desperate execs comb Los Angeles in the “Fox casting” truck, picking up derelicts, prostitutes and one disgruntled postal worker in a bloody uniform holding an AK-47 machine gun.

The cast is, in reality, a mix of stand-ups and sitcom refugees. Nicole Sullivan delivers a twisted monologue about how the first time she read Mad magazine was in a psych ward when she was a kid. But the really subversive stuff is in the parodies, the kind the magazine has always done so well. Orlando Jones and Phil LaMarr play tappers Ice-T and Ice Cube in a mock video that makes politically incorrect fun of rich, Perrier-swigging rap stars affecting ghetto-gangsta attitudes. The most brilliantly realized sendup, though, is “Gump Fiction,” in which a low-IQ thug named Forrest (David Herman) and his shrimp-obsessed sidekick (Jones again) go on a killing spree.

Not everything works. Animated versions of cartoons like “Spy vs. Spy” and Don Martin’s demented squiggles seem tamer than they did in the magazine: there’s sicker stuff on “The Simpsons.” But one revolutionary concept devised by “Mad TV” is sketches that last less than 15 minutes and have a beginning, middle and an end.

The other new Saturday-night competitor is Night Stand with Dick Dietrick, a syndicated parody of daytime talk shows that’s going up against “SNL” in New York, Chicago, Los Angeles and other humor-starved cities across the land. The concept is sharply executed (mostly by Tim Stack as the sleazy host), but aren’t talk shows self-parodic enough? A “Night Stand” episode titled “So You Think You’re a Lesbian . . .” could have been yesterday’s “Jerry Springer.” The whole thing feels too much like a sketch that goes on too long. In other words, too much like “SNL.”