Contrary to the official-looking memo making the rounds of federal agencies, President Reagan does not intend to turn the Pentagon into the world's largest nursing home.

Nor does his plan to make government workers stay on the job longer mean U.S. cafeterias will switch to salt-free food to accommodate an aging work force.

Here is the work-until-you-drop memo, which looks and reads like an Office of Management and Budget directive, that has amused some civil servants and frightened those who are suffering from the government's version of shellshock:

"In response to President Reagan's civil service reform program government employes can expect no authorized retirements until age 65 between now and 1984. Beginning in 1985 the minimum retirement age will be increased to age 75. After 1995, there will be no retirements whatsoever.

"Accordingly, the following actions will be implemented immediately with Priority One classification:

* The medical clinic will be converted to a geriatric unit. The current staff of physicians will be replaced with specialists in diseases of the aging.

* Ministers of all denominations will be hired and housed in each building on the installation. They will receive special training in administering last rites during flex-time duty hours.

* All printers, typewriters, etc., will be converted to 1/2-inch type size. All reports shall contain 1/2-inch-high characters as a minimum. Contractors shall be advised of this and their contracts modified immediately.

* Effective 3/2/83 all food served in cafeterias will be ground or pulverized and free of salt, sugar, pepper and all spices to accommodate eaters without teeth . . . . All food portions shall be at least six inches in diameter for visibility purposes. Vending machines shall dispense digestive aides.

* Every building shall be equipped on each floor with Geritol dispensers, oxygen tanks and stretchers. All halls shall be equipped with full-length handrails. Long halls shall have parking benches installed at 50-foot intervals for the weary to rest.

* All government vehicles used for personnel transportation and the headquarters shuttle will be converted to vans with wheelchair ramps.

* The employe store will sell toupees for men and wigs for women.

* The Face Lift Club is established to arrange for low-cost cosmetic surgery for very old employees who look very old.

* All telephones will be amplified 10 times.

* All orders shall be issued three times, spaced one day apart, to make sure that the employee remembers . . . .

* The seniority system based on years of experience is hereby abolished. Instead, all promotions shall be awarded solely on the basis of age. Adrenalin and other drugs will be administered, as required, to assure that the promoted individual knows that he/she has indeed been promoted.

* Lunch-time birth control seminars are abolished.

* The weekly symposium on Reagonomics is canceled because of lack of available speakers."

Bear in mind this memo is a joke. But the way things are going, maybe it isn't all that funny after all. . . .