AIN'T MISBEHAVIN' - At the Warner through July 15.

"Ain't Misbehavin'" is a streamliner that carries you through Fats Waller Land, from one show-stopper to another, without stopping.

The fare's not cheap - it starts at $9.50 and goes up fast and steep - but for your ticket you get more than 30 songs that Thomas Waller wrote, helped write or recorded; the 285-pound impact of his personality was such that no matter who wrote a song once he played it it was his.

The show rims canyons, with style, wit, charm and grace, as Waller did all his too short life. It's no wonder that two of the songs most identified with him were "Ain't Misbehavin'" and "Keepin' Out of Mischief Now": He was the sort of rascal who - dragged out of bed at the crack of noon, in a town he'd hardly had a chance to know - could knock back a few fingers of gin, listen to word-pictures of the neighborhoods (Piccadilly, Bond Street, Chelsea and so forth) and, within an hour, write and compose an impressive six-part London Suite.

Well, like its subject viewed from the late seventies of this century, "Ain't Misbehavin'" skirts caricature and stereotype all evening, so that your funnin' with Sportin' Life is shadowed with a fear of falling into Minstrel Land, until your fellow passengers take you from "Find Out What They Like" (which I, personally, hope every woman I ever meet will have seen, listened to and taken to heart) to a "dirty dozens" sort of ritual put-down ("Fat and Greasy") and then nail you in the solar plexus with the haunting "Black and Blue" - staged, lit, scored and sung in a way that will screw your head back on straight.

In two hours or so, you'll get a taste of life in pre-war (The War) Harlem, with its Cotton Club and its rent parties, served up by the biggest cast of five around, including a streetwise scamp, Ken Prymus, who acts as if he could give Fats Waller lessons to Fats Waller. When he smiles that smile, flashes those eyes and does those dimples, the house is his and he knows it.

The traveling party's enlivened by a six-man on-stage band, led by a genuine professor-at-the-piano, J. Leonard Oxley, and by a stunning set and lighting that doesn't just signal mood changes but changes your mood: In "Black and Blue," for instance, there's a feeling of being in front of a cathedral's front arch, underlining the notion of being locked out by God.

And there's a star at every stop. I was most touched by "Honeysuckle Rose," by Prymus and Yvette Freeman, a big, bouncy lady with a voice that plays brass and doubles on violin; "Squeeze Me," by Teresa Bowers, whose twinkle and poignance are matched by a startlingly bell-like voice; Ben Harney's amazingly liquid "Viper's Drag" - he could give Sammy Davis limber lessons: Adriane Lenox (a minx who describes herself as "a 22-year-old Virgo from Memphis") in everything all night; and everything about "Jitterbug Waltz."

The streamlined pace is appropriate, too, since Waller died on the Santa Fe Chief, heading east near Kansas City, at five in the morning (almost bedtime), at the age of 39, He'd made his first mark on Broadway at 25, and seldom slowed down in what little time remained to him. It was ten days before Christmas, wartime, when he died, and two of the songs in the show - "The Ladies Who Sing With the Band" and "When the Nylons Bloom Again" - were written in his last year of life.

How good is the show? How good was Fats Waller?

My only cavil, I guess, is that some good Waller pieces ("Blue Turning Gray Over You," for instance, and "Clothesline Ballet") aren't there, while some songs only "identified with" him are; but if the authors had followed that line,"'T Ain't Nobody's Biz-ness If I Do" would be out of the show, and that would leave a hole. And if, sometimes, Richard Maltby Jr.'s added-on lyrics seem a bit anachronistic - well, I can't think of any way the delicate and delicious "Jitterbug Waltz" could have been fitted in without the lyrics.

Anyway, I'm going to skip some other shows and invest the money in seeing "Ain't Misbehavin'" again. Maybe even twice.

If it's not sold out.