Levey's Third Law of newspapering has just been proven anew: A tantrum thrown by the Bob-ster soon produces an equal and opposite tantrum by a reader.

My fit of temper had to do with cashiers who make change by handing you several bills -- and then slapping change on top of those bills. To cope with this onslaught of money, you'd need three hands. Most of us are light by one.

Levey recommended that cashiers hand over bills, then wait three seconds, then hand over change. This would give people a chance to stow the bills before coping with the coins. The extra time is even more important because change probably goes into a different pocket or a different part of a purse from bills.

With the view from the other side of the counter, here's Erika Benitez. She's a 16-year-old Levey fan who works as a cashier. She says, rather modestly, that she has "a couple of complaints of my own." Erika's list:

1) "Decide what you really want to purchase before the cashier rings it up, not after." Erika says she has to void sales if customers change their minds. Bosses, she says, are not amused.

2) Do not take time to enter a check in your check register while you are still at the cash register. Erika says she constantly waits on customers who do this. Who gets the dirty looks? It isn't the customers.

3) Do not write a home phone number in the space between your printed name and the date on the check. Cashiers need this space to enter information about purchase and purchaser, Erika says. If customers "eat" this space before cashiers can get at it, a manager has to be called. Rush-hour-sized delays can result.

Erika didn't mention them, but here are a few customer sins that I'd like to add to her list:

4) Customers who wait until a purchase is rung up to begin hunting for cash or credit card. Rude and inconsiderate.

5) Customers who gather purchases into a lump on the checkout counter. The cashier has to de-lump the lump so purchases can be scanned or punched in one by one.

6) Customers who owe, say, $20.11. Instead of dropping a $20 bill and a $1 bill on the counter, these customers drop the 20 -- and then spend five minutes hunting for 11 pennies.

Thank you, Erika, for your right-on-the- button beefs. It always takes two to tango at the checkout register. Maybe now, some "customer is always right" types will realize that the customer who thinks he's always right is odds-on to be rude, too.

Paul Pinellas, of Manassas, overheard it outside the Air and Space Museum.

A bike messenger blew a rear tire as he crossed Independence Avenue. He limped to a stop across the street. He cursed his fate and his bike, in equally loud tones.

A man in a three-piece suit witnessed the entire affair, Paul says. He sauntered over to the messenger and said:

"Don't worry, son. You can always steal another one."

CHILDREN'S HOSPITAL

Calling all experienced "lieu-ies" -- and recruits who would like to join them.

Our annual fund-raising campaign on behalf of Children's Hospital has always depended on generous gifts from work mates. How terrific when someone passes the hat, not for the benefit of the football pool or the pizza fund, but to help sick kids get better.

Over the years, we have encouraged workmates to "grow" their group gifts by kicking in what they would have spent on holiday gifts and cards for each other. The theory: one more Hallmark card or $5 gift certificate will not make you tingle with emotion. But giving a sick child a fresh chance at life will make you tingle for years.

These no-gifts-no-cards donations are made "in lieu of" presents from one worker bee to another. So we call those who organize such campaigns "lieu-ies."

I heard from my first lieu-ie of the season the other day -- a woman in Columbia who wanted to get cooking and wanted to know how. Real simple, said the simple Simon who types this column. Collect money. Convert it into a check. Mail it. She said she'd do it that very day.

Why don't you do the same? It's a great way to get your office behind a great cause, to get a thank-you notice right here in Bob Levey's Washington and to nudge us closer to our goal.

You don't need my permission to become a lieu-ie, or credentials, or training. All you need is the will and a 33-cent stamp.

Have it at, lieu-ies. You've always been a key part of this campaign. I hope you will be in 1999-2000, too.

Our goal by Jan. 21: $650,000.

In hand as of Nov. 27: $51,515.15.

CONTRIBUTE TO THE CAMPAIGN:

Make a check or money order payable to Children's Hospital and mail it to Bob Levey, The Washington Post, Washington, D.C. 20071.

VISA OR MASTERCARD:

Call Post-Haste at 202-334-9000 on a touch-tone phone. Then punch in K-I-D-S, or 5437, and follow instructions.