Editor's note: CNN Contributor Bob Greene is a best-selling author whose books include "Late Edition: A Love Story" and "And You Know You Should Be Glad: A True Story of Lifelong Friendship."

(CNN) -- Your face may be about to get official corporate sponsorship.

Seriously.

It's the ultimate -- for now -- extension of American advertising relentlessness.

You may recall a column here earlier this year about a marketing executive's idea to put advertisements on the floors of the plastic bins that go on conveyor belts through airport security checkpoints -- the bins into which travelers must place their carry-on items.

I asked the executive, Joe Ambrefe, if he could think of any place that would be off limits to advertisers -- any place where placing an ad might be going too far.

"Not offhand," he said.

Some readers jokingly -- at least I hope they were joking -- came up with proposals for airport ads that would be even more intrusive than the security-line-bin ads.

One reader suggested that Transportation Security Administration screeners at airports wear jumpsuits festooned with big corporate logos, in the style of NASCAR drivers.

Another put forward the thought that when travelers are escorted to the new high-tech security-screening machines, they be forced to read out loud a sponsored advertising message printed on the wall of the machine, and not be allowed to proceed to their flight until they had pronounced every word.

Pretty funny ideas. But little did they, or I, know that a new kind of airport advertising was already about to be implemented, one that defies exaggeration. The first units have in recent weeks been installed at O'Hare International Airport in Chicago.

In the public restrooms.

The idea is this:

When a traveler walks into an airport restroom, he or she will see, over the sinks, where the mirrors are expected to be, big, vertical display ads for products. Some of the ads are still images; some are moving videos.

When the traveler walks to the sink to wash his or her hands, the ads become mirrors -- except that in front of the traveler's eyes the advertisements grow smaller, and move up to a corner of the mirrors.

Thus, the traveler is looking at his or her own face in the mirror, and also at the advertisement.

"We have chosen to be in bathrooms," said Brian Reid, the founder and president of Mirrus, the Huntersville, North Carolina, company that manufactures and markets the mirrors. "Bathrooms are often the last places people stop before they board an airplane, and the first places they visit when they get off an airplane."

Those travelers just about always stop to look at themselves in the mirrors above the sinks, Reid said. So why not turn those mirrors into advertisements?

Until the traveler steps in front of the mirror, it is a colorful, glassy-surfaced, full-frame ad, Reid said. But then, when an electronic sensor inside the mirror detects a body in front of it, the big advertisement "migrates to the upper left-hand corner." While the traveler is looking both at himself or herself, and at the ad in the corner of the mirror, "We track in real time how long [the traveler] is standing there," to determine how long the ad is being seen.

There is no camera inside the mirrors, he said, so no one at a remote location is looking at the person in the restroom. The sensors track only which advertisements are being seen, how many times, and for how long.

He said the mirrors are already being used in sports arenas in Texas, Georgia, Virginia and North Carolina ("in an arena, there are only two places people are guaranteed to visit: their seat, and the bathroom"), but that airports are where the big expansion is going to come. The O'Hare installation is just a start, he said, before a hoped-for rollout across the country.

He said that Clear Channel Airports, the big marketer of airport advertising, is his partner in the project, and that so far advertisers on the mirrors include Pepsi, Geico, Illy coffee, Microsoft, Pledge cleaning products, Zappos.com, Spanx women's undergarments and Dove men's care products. The airports share in the advertising revenues, and thus have an incentive to let the mirrors in.

And how do people react when they see an advertisement as they look at their own faces?

"Well, it is an unexpected sight," Reid said. "And some people do think, 'Gosh, is there no sacred place?' But we hope people realize that we have purposely chosen not to be around the toilet. We're over by the sink."

The marketing beauty of the idea, he said, is that when people are looking in the mirror, they are truly focused. What better time and place to pitch a product to them?

Asked whether people resent having corporate messages attached to their own likenesses in the mirror, Reid said he believes there is a psychological factor that may move people in our modern age to like being associated with a nationally famous product.

As for asking people directly, the first moment they see the mirrors, what they think of them, "We don't do interviews in the restrooms," he said.

But representatives of Mirrus and its marketers do occasionally stand outside the restrooms. And, according to Reid, one woman virtually ran out of a bathroom and said, wide-eyed, to her waiting husband:

"You are not going to believe this."

The opinions expressed in this commentary are solely those of Bob Greene.