Mary O'Neill wasn't sure she had handled the situation correctly. So she did what any sensible reader would do. She asked Robert Never-Wrong Levey for his thoughts.

Here they come, Mary, at a house-rocking shout:

You're 100 percent right.

If there were such a thing as 500 percent right, you'd be that, too.

As for that boob on the cell phone . . . If there were such a thing as 1 million percent wrong, she'd qualify.

Mary met her moment of doubt 11 days ago, in an office building at Friendship Heights. She had just visited a periodontist (translation: a mouth-hurter). She was waiting in the lobby, in pain, for her fiance to pick her up.

Important piece of the story: It was well after 5 p.m. So the front door to the building was locked.

All of a sudden, a woman approached the door. She was yammering into a cell phone. She knocked on the door and asked Mary (with her eyes) to please let her in.

Mary refused.

"My general rule of thumb is that if I see a stranger at a locked door and they don't have a key, I don't let them in," Mary said. "I wouldn't want people letting strangers into my office or apartment building. So why would I do that at someone else's building?"

Besides, a guard was in plain view, at the concierge's desk. Why beseech Mary when the woman could (and should) have besought the guard instead?

After a few more knocks, the guard opened the door. Without addressing Mary directly, the woman walked through the lobby, while screaming into her phone that she "can't believe how rude people are to sit there and not let her in!" Mary said.

"I don't let strangers into locked buildings," retorted Mary. But the woman continued to trash Mary, via cell phone, as she walked on.

I'm not sure Mary bought the building (or herself) much security by refusing to let the woman in. After all, the guard simply opened the door. He didn't ask the cell-phoner for an ID, a destination or her mother's maiden name.

Still, Mary is as right as rain. Any cop will tell you that the majority of crimes committed in office buildings and apartment houses begin when someone allows a stranger inside.

Vigilance is good. Carte blanche is bad. Take a bow, Mary. Take a hike, woman with cell phone.

CHILDREN'S HOSPITAL

Tidal waves and earthquakes are forces of nature. But around Washington, the strongest force of nature may be the end of a calendar year.

All over town, people see the word "December" and cringe. "Whoops!" they cry. "I have six days of leave sitting in the hopper. Better use it or lose it."

Which is why, for all practical purposes, this is the final workday of 2002. If last Friday wasn't.

Before you head for the airport or the open road, I'd be grateful if all worker bees would remember the sick kids at Children's Hospital.

Group gifts amassed in the workplace are the backbone of our annual drive on behalf of Children's. They don't have to be as large as the gross national product. We're very grateful for whatever workplaces can manage to put together.

But we do have a record goal on the table this year. So help is welcome -- especially if your crew hasn't contributed previously.

Please remember the kids at Children's before you hit the door. Pass the hat, then send me the proceeds, via any of the methods listed below. The money helps pay bills of Children's patients whose families cannot. It never goes to another purpose.

Isn't this what the phrase "holiday spirit" really means? I certainly think so, and I think you'd find very few doubters around your office. Thanks in advance for supporting our campaign.

Another activity sure to play out today: office parties. A frequent agenda item at those parties: gift exchanges.

You'll forgive me, but these are usually lame in the extreme. X buys Y a $10 tie or a $7 bottle of perfume that smells like bathtub gin. It's cheer on the cheap. It's so expected that it loses any sense of mirth and joy.

What if I told you that your office should pool the money it would have spent on gift exchanges (and holiday card exchanges) and give it to Children's Hospital instead?

We net thousands of dollars this way, every year. If your group of officemates goes the "in lieu of" route, I'll mention your generosity and smarts right here in Bob Levey's Washington.

I call the people who put such gifts together "lieu-ies," because they assemble gifts in lieu of office exchanges. If you'd like to name yourself the "lieu-ie" at your place of employment, hey, come on in, the water's fine. Thanks very much.

Our goal by Jan. 24: $1,000,000.

In hand as of Dec. 20: $273,693.55.

TO CONTRIBUTE TO THE CAMPAIGN:

Make a check or money order payable to

Children's Hospital and mail it to

Bob Levey's Campaign for Children's,

P.O. Box 75528, Baltimore, Md. 21275-5528.

BY 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.

TO CONTRIBUTE ONLINE:

Go to www.washingtonpost.com/childrenshospital and follow instructions.