FRED WILLARD looks not at all like a show-biz slickie and quite a bit like an accountant pretending to be a secret agent. "People used to think I was a plain-clothes policeman," he says. "I like to think people who don't know me think I'm a professional athlete. I always wanted to be a ball player."

That's not the role that fate and Noman Lear chose for him, however. Willard, 38, plays achingly overripe second-banana Jerry Hubbard to Martin Mull's smug Barth Gimble on "America 2Night," the intentionally tacky talk show that started as "ferwood 2Night" and premiere at 7:30 p.m. tomorrow on Channel 20 here and in 45 other TV markets.

It's surprising to find that Willard, who is also a member of the satirical Ace Trucking Company troupe, is such an all-American staright-arrow type, because he lampoons The Perfect Square so wickedly on the show, Jerry Hubbard is a bouncing baby-faced dolt, lovably infallible when it comes to always saying exactly the wrong thing. He's a trusting, bumbling shmoe and the funniest thing on the program.

Funnier, certainly, that Martin Mull. "My friends say, 'Oh God, you should be the host of the show' and and I imagine Martin's frineds are saying, 'Get rid of that guy!'" Willard says. THe idea of a Mull-Willard feud is pretty attractive since, on the program, Gimble can't stand his hapless shadow and Hubbard can't wait to graduate from the Ed position to the Johnny spot.

So what is Mull really like ? "Turn off that tape recorder," says Willard, "and I'll tell you stroies that'sll - "

Okay, it's off (heh-heh).

Willard draws back. "Martin Mull THE MOST POMPOUS - no, he's wonderful. Martin makes me feel good on the show. DUring a commercial, I'll say, 'What do you think, is this funny"' and he'll say, 'Oh, do it, do it!' He's very generous and wonderful to work with, because you can't throw him.

"The show is scripted but a lot of it is ad-lib-bed. SOmetimes they'll come up and say there's a minute to kill between the last guest and the commercial so maybe I'll say, 'What if I said this?" and he'll say, 'Oh yes, perfect,' or the other way around. Occasionally Martin, during acommercial, he'll make some comment that he wants to come on and do a joke about Totie FIelds, and I say, 'I don't think you ought to do that.' He's outrageous, yeah, although outrageousness is getting so common in television that eh program's humor seems not so much sick as just a little ill. THe very first "Fernwood 2Night" featured a guest who played the piano from an iron lung. The first of week of "America 2Night" includes a running contest to see which lucky viewers will get to pull the wsitch that extinguishes a convicted murderer on Friday night.

"Well, the death-row bit is a funny thing," Willard says. "The iron lung? I loved that, because the guy wasn't the least bit sympathetic. He has his concert career and he said, 'I'm sitting pretty now.' When we taped the first show, we were supposed to come back after one commercial dna you heard this man gasping for breath and then the camera shows little Baby Irene, the child star, holding the plug for the iron lung. Then they plug it in and he recovers, and when he gave the high sign to the camera, I must have sat there for 10 minutes laughing. But Norman Lear made them change it. He though it was too offensive."

"America 2Night" will eve more of a "Pirandello kind of thing," as Willard puts it, that "Fernwood 2Night" because actual Hollywood stars come on the show and sit side by side with phony stars. On the first show, Charlton Heston proves a surprisingly good sport as he is badgered with mononic questions by Jerry Hubbard; there's a delightful show of Heston impatiently checking the time on his watch.

"Most of the guests have been wonderful," says Willard. "Robert Conrad (of 'Black Sheep Squadron') 'was a bit of a pain in the neck, though, I thought. He said, 'I'll do anything, I'll do anything, I'll come on and have fun, and the idea is not for him to have fun, it's for all fo use to have fun together. So he wouldn't rehearse, eh wouldn't do anything. We planned a thing where he was supposed to have injured himself doing a stunt and been shot full of tranquilizer so that he comes out on the couch and keeps falling asleep while I try to interview him.

"And I was supposed ot want his autograph so at the end of the show I'd go over and, you know, put the pen in his hand while he was out cold and sign his name. But I said, 'That doesn't sound like something he'll want to do.' He came out and he didn't know what he wanted to do. He'd get on the couch and pass out but then I'd make a joke and he'd pop right up and try to top it. Anytime there was a break, he'd leap off the couch and run over to the fans, because all the girls in the stands were screaming over him. Then right at the end of the show he was supposed to be completely unconscious and Jerry says, 'Hey, this would be a good time to knock that battery off his shoulder,' you know that commercial, and then of course he had to sit up like he was going to fight - missing the whole point and ruining the whole thing."

One of the repeating jokes of the series is the shamelessness with which the cohosts plug products in the hopes of getting them free - a Sony Betamax, for instance. There is a lot of plug lampooning during the show, but then over the closing credits, announcer Hubbard, or is it announcer Willard, has to do real plugs for real products.

The rewarding things about the program, in addition to Willard's fumble-bumble Hubard, is the meriness with which it zaps some of television's phoniest baloney. As Willard notes, "You never see a character like Maertin so shallow and obvious in what he's trying to do. It's refreshing to see someone so, I don't know - so honestly dishonest."

Whether viewers will want to avail themselves of this packaged whack at packaging five nights a week remains to be seen, but "America 2Night" does have a certain vicious charm, and it's funnier than many of the most successful prime-time network comedies, that's for sure.One hopes that the role of Frank De Vol's woebegone bandleader Happy Kyne ("and his Mirth Makers") will be edpanded, especially if it's at the expense of Mull's tiring smirk sessions. On the fifth show, Kyne is surprised with an appearance from his long-lost niece Joanie, whom he hadn't seen since she was a baby. It turns out Joanie is an into-leather thuggette who sings a punk-rock version of "My Favorite Things."

Happy cowers.

We can expect more from Willard as well. He will step out of his announcer's boots at least once in the future, he says, to lip-synch a record. The song? "I Gotta Be Me" - as recorded by somebody else, of course.