I was diligently clipping the "10-cents-off" store coupons in The Post Sunday when I discovered that for as little as $10.95 and three labels I could order a Heinz Ketchup Bottle Telephone.

The "telephone," a perfect replica of the red-and-white tomato bottle I have known and loved since childhood, has the push buttons in the base and nine little holes in the neck where, I assume, you listen.

Should you be skeptical that a ketchup bottle can really be a telephone, too, the ad hastens to reassure you that its features include push-button dialing, automatic redial, a mute/privacy button, FCC approval and a 90-day warranty.

Well, the FCC may be ready for a ketchup bottle telephone, but I am not. Suppose the president or the governor or the mayor or my conressman called me at home to ask why we had written this or that in the paper. Would I want to discuss affairs of state on a ketchup bottle?

Or, suppose my neighbor were to drop in and ask if she could use our phone. What would I say, "Sure, be our guest," and then hand her a ketchup bottle?

And what of those times when it requires all your diplomacy to say "no" on the phone to mutual fund salesmen, alumni association solicitors and the local civic association president who wants you to become chairman of the Swimming Pool Cleanup Committee. Can you really maintain your poise and dignity with a ketchup bottle in hand?

During the past few years, I have watched nervously as the old black dial telephone gave way to push-button designs in many colors and shapes. My uneasiness increased when I toured a phone store and discovered there were Mickey Mouse and Snoopy phones, desk phones hidden in fancy walnut boxes and French-style telephones that would be right at home in the boudoir of Mme. La Fifi.

Soon thereafter, Ma Bell and her brood went their separate ways. Suddenly, you could rent your phones or buy your phones or turn in your phones or design your own phones. Fortunately, Andy Griffith, on behalf of AT&T, was there on TV frequently to reassure me that all I had to do was to sit back and relax, so I did nothing. But all the while, my sons were busy installing cordless phones in their homes and answering my calls while mowing the lawn or changing the oil in their cars.

If I haven't already missed it, I am sure there are or probably will be telephones that look like Coke cans, Crest toothpaste tubes, Johnson Baby Oil bottles, Quaker State Motor Oil cans, Rice Krispies boxes, Pepto Bismol and even Sani-Flush. Help!

Surely, if we already have ketchup telephones, the toy people can't be far behind. Even now, there must be designs for telephones shaped like Captain Kirk and Mr. Spock, Superman and G.I. Joe. And so, who will be surprised to find a Ronald Reagan telephone or a Walter Mondale or Jesse Jackson phone on his desk?

Perhaps, in some oppressive society of the future, all citizens will be required to own and use telephones in the shape of their national leader, as a reminder of what they are allowed to say and not say out loud. In such a society, a revolution would require more than the obligatory changing of pictures on the wall -- the new leader would have to replace all of the phones, as well.

And so I wonder: If Alexander Graham Bell had foreseen that his invention one day would turn into a ketchup bottle, would he have uttered those historic words, "Mr. Watson, come here. I want you." He might have looked at his embryonic transmitter and hung up, declaring: "Sorry, wrong number."