READING THIS BOOK is like spending a week at an American Legion convention. For the first few hours, the boys are amusing in their "Mademoiselle from Armentieres" way. But the next six-and-a-half days are as much fun as having a drunken salesman blow whiskey and cigarette fumes at you as he stands too close telling a joke that refuses to end.

Four hundred pages of sports writer's English, if imbibed all at once, may kill brain cells. In drunk Before Noon , people don't work, they hang their hat and tie at the such and such office. Women are members of the gentler sex. Old people are old-timers; long-time members or employes are stalwarts -- all in a world where you may find a tough cookie with a heart off gold and where on is always in danger of winding up with egg on his face, especially if he is the prez and is caught out by a news lassie, probably one who doesn't walk this city but prowls it for news.

This book is so dull it should have been subtitled "The Behind-the-Scenes Story of the Washington Press Corpse," or did you want to know that Helen Thomas was the 1975 Ladies Home Journal Woman-of-the-year in Communications? The book is stuffed with similiar biographical information about well-known Washington news people. But not a word about Thomas' sex life, no disgracefully irresponsible story about Jack Anderson.

The only salacioulsy outrageous gossip in the book comes from stories told by Gaston B. Means, a feloniously mendacious ex-con, about major figures of the Harding period. Means' accusation that Warren Gamaliel, himself a newspaper man, was murdered by his wife has been discredited, and that out authors should point to the publication of Means' myth-telling as an early example of investigative reporting is to giggle. In a book of this nature, the rule should be: Speak truth of the dead; only lie about the living.

Drunk Before Noon is soberly organized. Indeed, with a chapter given over to wire services, another to investigative reporting, another to investigative reporting, another to columnists, the thing might be a J-school text, save it contains so little useful information. There is even a chapter on public relations. Such encyclopedic inclusiveness serves no other readily deductible purpose than emission of flattering gas bubbles about the author's friends, or famous people the authors wish were their friends. Between the covers of this book lie more plugs and favorable mentions than a year of Merv Griffin and Dick Cavett. Not that this endless, insipid name dropping doesn't stumble into an amusing line every couple of hundred pages: "Around Washington, they call Carl Rowan the black Jack Anderson." They do, do they? I know people at the other end of town who call Jack Anderson, the white Carl Rowan.

It's less a book than a product offered for sale by a marketing team. It's manufactures seem to have studied every recent Washington best seller and put a little of the same in their confection. Ergo, we read:

"The Hill, never a hotbed of chastity, has become a lively place since the sexual revolution. The great increase in personnel and the accent on women in responsible jobs brings hordes of above-average career girls who crage more action than they can get from jaded congressmen . . . Girls looking for dates and to be taken home are plentful at after-hours parties held in Committee rooms, such as the Friday meeting of Poets -- Piss on Everything, Tomorrow's Saturday. One of my friends was pursued by an eager chick as he left to call home. She burst into the phone booth, unzipped him, and performed an unlady-like act before he could protest . . ." His slowness to protest is because he stutters, a condition frequently found amoung those driven from the hotbeds of chastity by jaded congressmen and above-average career chicks craving an opportunity to commit unlady-like acts.

If journalists are slow to return home to their spice of a Friday night, either because they have rendered themselves speechlessly incapacitated with alcohol, or because they have barricaded themselves in phone booths to save themselves from rape by members of the legislative branch of government, our authors explain why this needs be: "Goodness knows the hardworking reporters can use a little nonsense to counteract the tensions of covering an ever-nervous and fitful Washington."

The hard-squinting reader deserves a little nonsense, too, but he won't get it in this effort, the heaviest volume of light reading you'll ever fall asleep over.