I OWE WHATEVER sanity I possess to my commuting habits. If ever I drive a car inside the Beltway between dawn Monday and sunset Friday, it's for a very good reason. The subway transports my corpulent corpus from home to work and back again just fine, thank you.

But when you're 100 feet down in a tunnel, you miss the latest in automotive trendiness. The other day, while forced to spend 20 halting, harrowing, horrifying minutes on the Beltway, I saw several of those yellow BABY ON BOARD thingies bobbing in the rear windows of cars.

I'm told that these are all the rage. The surest sign is that pale imitators have begun to crop up. SINGLE WOMAN ON BOARD. SUPERSTUD ON BOARD. Even EX-WIFE IN TRUNK.

But BABY ON BOARD seems to be by far the most common of the breed. And Harry L. Haley of Alexandria thinks he knows why.

"The intent, I believe, is in case of accident and incapacitation of the adult, a rescuer can save the baby," Harry writes. However, Harry notes that most of the time he has seen B.O.B. on display, there's no baby inside the car.

"I would hate to think of a good Samaritan being injured or killed going back to a wreck for a baby that wasn't there," Harry says. "Could you ask in your column that the sign be displayed only when a baby is actually in the car, please?"

Just did it, Harry, and I'm happy to. But I have a sneaking hunch your premise is wrong.

I don't think people display B.O.B. so that their little dears will be rescued. I think they display the sign for two other reasons: 1) Parental pride and 2) Parental pleading with lunatics to slow down so they won't smash into the baby-bearing buggy.

How about it, readers? Is Harry right? Am I? Neither of us? Please let this poor nondriver know.

Classic Washington story, courtesy of Bob Sargeant:

Bob works in a high-rise office building in Springfield. The building is equipped with a smoke detector/fire alarm system that's the bestest with the latest and the mostest.

On June 18, the system started flashing, chiming and whatever else it's programmed to do. Bob and friends later discovered that there was no fire -- only some smoke wafting into the ventilation system from a brush fire in a nearby vacant lot. But the troops didn't know that at the time. So, as the bells and whistles were going off, each worker had a fleeting moment in which to grab A Special Something from his desk before stampeding for the exits.

One guy chose the pictures of his kids.

Another guy chose the pictures of his wife.

Kym DeWaard thought for a second. Then she chose her Rolodex.

Warning: What follows is a love letter. From me. To all of you.

Sunday marks the fifth anniversary of Bob Levey's Washington. But since Saturday and Sunday are my "dry days" each week, I thought I'd better emulate that old TV quiz show and get as close to the anniversary day as I could without going over.

When I sat down in June 1981 to write the first B.L.'s W., I really had no idea how it (or its successors) would be received. Truly, writing a five-a-week newspaper column is like fishing. You bait the hook, you heave it out there, you sit down on a nice piece of grass and you wait. Maybe you get a nibble, maybe you don't.

For this kid, the nibbling started the first day, and it has never stopped. You readers have been absolutely terrific. You have praised me on the few occasions I've deserved it. You have kicked my posterior on the many occasions I've deserved that. You have made the fishing analogy inoperative. I no longer have to heave and hope. You're out there. I know it. And it's a beautiful thing to know.

What I've tried to do for five years is to write a column that's accessible, the way Louie's corner bar is accessible. No pronouncements wrapped in purple. No agendas the president absolutely must adopt before he finishes shaving this morning. Just honest truth about a city that I happen to think is fabulous fodder, and a fabulous place to live.

The greatest satisfaction I've gotten in this half-decade has been to sense that you readers have caught my drift. You don't hesitate to pick up the phone or pick up a pen -- and if you ever do, I'll know I'm doing it wrong.

The first piece of advice I ever got as a columnist was never to publish my phone number. It was a piece of advice I hastened to ignore, and I'm about to ignore it again.

Any time something tickles you or tackles you, any time a wrong needs righting, any time you think you have a story that deserves a wider airing, any time you just need an ear, I'm at 334-7276.

Please know what a pleasure you readers have made these five years. Five more? With a bunch like you, that's the silliest question I've ever heard.