It isn't hard at all to get in the proper frame of mind for "Neighbors." All one has to do is spend 15 minutes walking in the city or 20 minutes driving in the suburbs. Before long the inescapable conclusion dawns on you that 3 out of 5 people alive today are sheer stark-raving stark ravers. They're nuts. They're crackers, bananas; they're totally insane.

They have taken leave of their senses.

Once in the proper mood for "Neighbors," however, the disappointing discovery is that there isn't a lot of movie there. "Neighbors," now at area theaters, is by no means a laughless debacle like "Buddy Buddy," and as an ambiguous paranoid rattle around life's great cage, the film is funnier and less pretentious than "Being There." It's just too bad that it tends to send you home empty-headed.

John Belushi and Dan Aykroyd, two of the most combustive comic finds from the old "Saturday Night Live" show, are teamed for their first major dual vehicle since "The Blues Brothers" in the film, adapted by Larry Gelbart from a Thomas Berger novel about nuttily nightmarish goings-on at a desolate suburban cul-de-sac -- "the end of the road," as it is called more than once in the film. Gelbart, better known for his television work, doesn't seem particularly comfortable with the situation here. Reports that Aykroyd helped on the screenplay might explain such touches as a casual reference to Arthur Bremer and new definitions for words like "chew," "unit" and "pork" (as a verb).

Belushi plays an up-tight suburban homeowner whose safe, dull existence is suddenly disrupted by the appearance of new neighbors in the huge pile of bourgeois gingerbread next door: specifically, Dan Aykroyd with his hair dyed wild blond and Cathy Moriarty ("Raging Bull," though not the title role) making with tantalizingly (later monotonously) seductive purrs from her first appearance.

The husband insinuates himself with all the subtlety of a Pentagon cost overrun, and the wife stays on a temptress wavelength no matter what. Belushi's hapless Earl Keese is at first baffled, then -- when the new neighbor takes 32 bucks from him to buy take-out Italian food and then sneaks home to cook the meal himself -- angered, then, unconvincingly, entranced. "I really had a good time," he says to the new neighbor after a night of hysterics and aggravated assault.

Belushi is amusingly and productively cast against type; audiences will be waiting for this meek, put-upon shmoe to explode. When he does, the payoff is a kick because of the protracted simmering buildup. Preparing for what he thinks will be a heavy date with his neighbor's wife, Belushi carelessly ravages his face with his wife's leg shaver; he splashes some after-shave on his face and then, yow. Belushi explodes balletically, the way Jackie Gleason used to explode when Norton dropped a bowling ball on his foot.

Both Aykroyd and Belushi are nothing here if not consistent; they seem practically obsessive, like deep-in-thought chess players, and so they earn Gelbart, and the styleless director, John G. Avildsen, repeated extensions on the old suspension of disbelief. But eventually, the gambit catches up with itself. The vaguely allegorical pretentions of the screenplay require too much rigidity in the actors. And at some point, say three-quarters of the way through, the script needs to be more explicit about whatever it's trying to say concerning air pockets in the American middle-class dream.

One conceivable source of clarification, Earl Keese's wife, is a throwaway character as written and a mere dithery nuisance as played by the miscast Kathryn Walker.

TV commercials for the movie use a "Twilight Zone" motif and a Rod Serling sound-alike announcer. In fact the film would be better off if it had some of the stylistic and conceptual coherence of the better "Twilight Zone" episodes. The opening shot suggests wry and witty possibilities: The two drastically contrasting houses sit side by side with a huge electrical tower standing monstrously between them. The tower, which occasionally spritzes out sparks and ominous buzzing, may have something to do with, oh, DEATH, but the script and direction aren't sufficiently provocative to inspire much serious speculation.

For the record, the film is preceded by a selection of rave reviews for the book -- apparently a new cross-promotional device, but in this case giving the appearance of preventive apologia, as if to say, "This won't make much sense to you, folks, but it's really very profound." Also, the executive producers are Bernie Brillstein and Irving "Swifty" Lazar, two Hollywood agents. Congress might want to consider whether Hollywood agents, singly or in pairs, should be allowed to produce motion pictures.