Steve Allen has just finished a banana and is lying upsy-daisy on a slant board so blood will rush to his head. A man enters the dressing room brandishing three pairs of gaudy men's boxer shorts. "Does one of these strike you as funnier than the other one?" The man asks Allen. He puts on his glasses, looks up at the underwear and says. "They're all equally hysterical."

Allen, 59 now, brings more than 40 years of show business experience to crucial decisions like that one. He's making lots of them for NBC's upcoming and greatly needed "Steve Allen Comedy Hour," an attempt to revive entertainment on television. Originally Allen and company were only to do one pilot show (to be seen tonight at 10 on Channel 4), but a drought brought on by the actors' strike led NBC to order five more.

So at a small Vine Street theater in Hollywood, Allen, costars and crew are rehearsing a little mayhem with which to convulse a republic. Allen -- in baggy khakis, a sloppy corduroy coat and an untucked shirt hanging out -- is everywhere at the rehearsal, adjusting camera shots, ordering up larger one cards, dashing back to a yellow piano on stage for some musical noodling during breaks. His company, Meadowlane Enterprises, is producing the show.

"It is possible to rheostat that dynabeam down seven degrees or so?" a blinded Allen asks a lighting man at one point. "The cue for the bottom will be, 'Gunther Krellman,'" he tells the guy in charge of the "Applause" sign overhead. And during a restaurant sketch, when the director has pulled in too far with his camera and is getting a shot of an actor's stomach, Allen lays down a law of TV comedy for him: "No closer than this," he says, once the camera has pulled back."We want to see funny people with funny faces doing these funny things."

One of the regulars from Allen's illustrious old repertory company of cutups, Louis Nye, is standing around in full Japanese drag, even though they're rehearsing a sketch about a German stunt pilot. Nye looks up at the towering (6 feet, 3 inches) Allen with those wonderful downtrodden eyebrows of his and then sparks into the old nuttiness once the rehearsal begins. Guest star Donald O'Connor, seated at a piano, looks up at a picture of himself on a monitor and says, I'm getting to look like an older me."

Allen unquestionably rules this roost; he even gives directions to the director. He orders up new props, grumbles about cigarette smoke where there is none, and tells the cue-card man to stand so that the studio audience won't be able to read the cards along with him. Some might consider him insufferable, but when it comes to comedy, who knows more than he?

It was Allen's steady, valorous professionalism that saved this year's Emmy Awards from debacle. Striking and boycotting actors made the show almost starless, but Allen's nimble mind and cosmetic smarts rushed to the rescue -- at the last minute, as it happens. Allen only agreed to do the show two days before broadcast and then only on his terms, which included a statement of support for the actors and the donation of his fee to their strike fund.

"At that point, they were desperate, they had to agree to everything," Allen recalls. "And yet Sunday afternoon, I almost walked off the show. We were writing jokes, and some network guy came in and said, 'I'm sorry, Steve, but no Fred Silverman jokes.' I said, 'Fellas, all the luck in the world, but goodbye.'" The show and Allen went on, Fred Silverman jokes and all.

"The more things are going to hell all around me, the easier it is for me to get laughs for some reason," Allen says. "In a nightclub, if a woman at a front table gets up to go to the bathroom in the middle of the act, and you know what you're doing, you can make that work for you without hurting her feelings or anything like that." Well, the Emmy show was like three hours of people getting up and going to the bathroom.

All his life, or most of it, Allen has been masterminding this kind of mischief, in between writing two dozen books, composing hundreds of songs, doing live performances, and the PBS series, "Meeting of Minds." Backstage, he is asked if TV variety shows aren't beyond salvation -- in the last few years, Mary Tyler Moore, Dick Clark and the amassed resources of NBC's "Big Show" have all flopped.

But this is not a variety show, Allen notes -- it's a comedy show. "With all due respect to Ed Sullivan, who was great, I think the age of the pointer is over. That time I think is passed; why, I don't know. But I think comedy is very hot now, especially for people under 35. They even have their own Henny Youngman: Rodney Dangerfield.

"I'm not a professional host, I'm a professional comedian. I've been doing basically the same damn stuff for 35 years, but for some reason it never seems old-fashioned. My comedy has always appealed to the hip and to the silly, whether it's 9-year-olds who dig the silliness, or high-school and college kids who dig the hipness. People under 30 have always been my particular fans."

Is Allen, always politically active, involved in the current presidential campaigning? "I wake up every morning sick to my stomach," he says, "if you call that being involved. We are living in a dumb time in American history. I fear we're getting dumber as a people."

Allen is also dismayed by the quality of current TV comedies. "It's far too dirty for my tastes," he says. "A lot of the younger comics are deliberately going for the ain't-we-naughty kind of stuff. When I go to the Comedy Club and see the young comics, I'm appalled at the degree to which filth is a part of their acts.

I love sex.I know that sounds silly, but there are all kinds of things we do in our lives that we shouldn't want to see on the stage." He sighs a slightly professorial sigh and says, "It's part of the whole moral collapse of our culture."

It all sounds gloomy -- but, a few minutes later, Allen is back on stage trying, as it were, to make some sense out of it all by reducing life to its principal ridiculous ingredients -- an indispensable service to the human race, perhaps now more than ever.