The latest thing in Sick Chic and what might be called Television of Cruelty is also the sneeringest Norman Lear show yet, "Fernwood 2Night" seems bent on talking pokes at the eyes that watch it.

You can't blame the people who won't want to be poked, although there is something faintly lovable about the show's lust to offend. "Fernwood 2Night," premiering at 8 o'clock tonight on Channel 20, uses the mythical setting of Fernwood. Ohio, and the talk-show format to skewer a definitely finite number of tonics, including small-town bigotry and the banalities of what host Martin Mull calls "this crazy business of show."

Holding nothing scared is a pose more tolerable in theory than in practice "Fernwood" springs from a mentality so jaded and valueless that it's hard to know how to take it, or whether to bother trying. Its apparent contempt for middle-class moves will alienate many of those at whom its commercials are aimed, and it may have to depend on misanthropes and masochists for an audience.

Still coming across an actual idea, even a half-baked or half-realized one, is such a novelty in summertime television that the program may deserve a special dispensation. Then, too, it is by definition a terminal illness, bridging the gap between "Mary Hartman," which concluded last week, and "Fernwood, U.S.A.," which starts in the fall.

The first week's shows run the gamut from the bizarre to the grotesque and have moments that are criminally and corrosively funny. Tonight's guests include a man who plays the piano from an iron lung and "a Jewish person of the Hebrew faith" considered such a rarity in uptight Fernwood that he is brought on so viewers can phone in questions.

"Hello," says Mull into the telephone, "'Talk to a Jew' - you're on the air."

The most welcome guest on the premiere is Dabney Coleman, at his sickeningly evangelistic best in the role of Fernwood Mayor Merie Jeeter. On the second show, a fictitious doctor maintains that leisure suits cause cancer but says a "laetrile leisure suit" is being developed. And a married couple plead that their 37-year old son be deprogrammed from the Catholic faith, even though he's been a priest for the past 14 years.

Ghastly "Baby Irene" tap-dances around the iron lung to close the second show. The fourth includes a visit from "Mian Co Tiam," Vietnamese author of "Yankee Doodle Gook."

Obviously, "Fernwood 2Night" represents a new infusion of sick comedy into mainstream American humor. Unfortunately we may have passed the point where being audacious on television is its own reward. "Fernwood" gets desperate in the desire to startle; too often the writers forget they should also try to be amusing.

Mull, playing his "Mary Hartman" character of Barth Gimble, is a problem, too, as the host - mumbling, mugging, ineffectual, and always waiting for the camera to be on himself. Far funnier and more perceptibly satirical is sidekick Jerry Hubbard, played by Fred Wiilard of the defunct Ace Trucking Company. Williard, with big foot firmly in fat mouth, gets the best if nastiest lines.

To "real, live Jew" Morton Rose, Willard blunders. "You look just like the rest of us.It's as plain as the nose on your face." He praises the iron-lung pianist for his "wonderful laidback style." He tells a young black. "I saw the TV show "Roots" and I thought your people came off pretty good," and remarks to the Vietnamese guest. "You aren't really like us: you're much smaller."

Production details spoof small-time TV: sparkly scquined signs, a studio audience armed with shopping bags, cards that tell viewers "Don't Go Away" and "We're Back." There are folding TV trays on the patchwork living room sets the backdrop is a grim rendering of the Fernwood Assembley Plant.

Probably the funniest detail, though, is composer-conductor Frank De Vol's portrayal of whebegone band leader Happy Knne who, with his "Merry Makers," stomps out a wonderfully Weikian arrangement of the disco hit "Shake Your Body" that is the most hilarious thing on the premiere show.

Do Vol and Willard contribute an air of diligent, congenial nuttiness that cuts through the program's basic cynicism and helps it a viewpoint. They work at corss purposes with [WORD ILLEGIBLE] , who appears intent on proving television is beneath him. Direction and waiting on the first week's show are sloppy and lax.

For the writers will out-outrageous themselves in weeks to come could prove boring or fascinating. ABC's forthcoming fall series "Soap" is supposed to be more outrageous yet and is already kicking up controversy. It's beginning to look as if TV will be using sick humor and bad taste the way it's been using violence, and if that happens, we may all find ourselves yearning for the sweet simplicity of a bullet to a bad-guy's brain. "Fernwood2Night" could be the misshapen shape of things to come.