The annual dinners of the Gridiron Club, such as that held Saturday night, are supposed to be off the record: Nothing said there is supposed to be repeated. But if you read yesterday's paper, with full-blown quotations from those such as President Reagan and Ted Kennedy, you know that there is more a gusher than a leak.

Once upon a time, after the Gridiron of Nov. 27, 1887, nobody repeated anything that was said. There was a very good reason. Let's explain, in the words of retired Birmingham News correspondent James Free, historian of the Gridiron, in his 1985 centennial book of club history:

"Guests that evening included a Chinese diplomat, Yow Jiar Shee, and the French author Paul Blouet . . . . Since the diplomat's command of English was weak, he had indicated he would speak in his native Chinese. He did so with great intensity and frequent pauses.

"His listeners sensed humor in the fact that they understood not one word.

"They were aware, too, that pauses in an impassioned speech usually bring some audience reaction. So they began to punctuate with applause -- lightly at first. Then, when Yow Jiar Shee started smiling, they clapped with more vigor. At the end, they shouted approval.

"M. Blouet, perhaps influenced by the Chinese diplomat's successful example, elected to speak in his native French. The audience responded more quickly this time, perhaps because a few listeners understood French and could provide the cues. To all appearances, his message aroused great enthusiasm.

"When it was over, speakers and listeners alike were highly pleased with the results.

"Members of the club felt even more pleasure later when M. Blouet, in a book about his experiences in the United States, wrote that the Gridiron audience evidently was as familiar with French and Chinese as with English." Medium Undone

As regular readers know, it isn't the message, it's the medium -- such as illegally posted broadsides -- that often ticks off Metro Scene. So we're righteously annoyed by stick-on strips posted on and partly obscuring several Capitol Hill parking restriction signs that, as recently as yesterday morning, proclaimed, "Support Freedom Fighters" and "Support President Reagan." And we salute the contractor of a building job at 15th and K streets NW who finally painted over spray-painted graffiti on a construction fence that expressed the opposite view. Special Egg Hunt

If this item alerts the family of just one blind youngster, though we hope it reaches more, it's newsprint space well used.

On Saturday, the National Park Service's U.S. Park Police and the Alexander Graham Bell chapter of the Telephone Pioneers of America will sponsor their eighth annual Easter egg hunt for blind children from 10 a.m. to 1 p.m. at the Sylvan Theater on the Washington Monument grounds.

The hunt features the use of specially designed egg-shaped devices that emit beeping sounds, permitting blind youngsters aged 6 and upward to find them. All participants will get prizes.

For further information on participation, contact Park Police Officer Kenneth Perry at 472-5786.