The Hexagon Show is 25 years old, and on the evidence of the production currently kicking up its heels at Georgetown's Trinity Theatre, this is a Washington tradition worth hanging into.

The 1980 version's is to raise money for Second Genesis, the drug rehabilitation program, but it is also, tangentially, an emphatic demonstration that zealous, unpretentious amateurism has it over mediocre professionalism any day of the week.

Inspiration, of course, coexists with abomination. That's what amateurism is about. But at the "Saturday Night" show reminds us whenever it can, that's what professionalism is frequently about, too.

"Tongue in Cheek," Hexagon's Silver Anniversary Show, hs borrowed more than a few of its schematic ideas from "Saturday Night," but it has made the loan pay off. Newscasters Timothy Rice and Martha Manning do a recurring sketch called "Hexagon Update," for example, that includes a report on trouble at California's controversial high-class sperm bank. "Less intelligent sperm," they inform us, "have been complaining that the Nobel sperm have been keeping them awake nights singing Gregorian chants and reading Camus."

In the musical department, Jim McKnight (who is also this year's director) has provided a complete Gilbert and Sullivan-like operetta on nuclear power and a delightfully deadpan oratorio, called "Sic Transit Gloria Sunday," chronicling the rise, fall, rise, fall, rise, fall, and (fingers crossed) rise of Joe Theismann as a messiah. In the latter, a vast chorus pleads with the savior, in one of his less promising periods, to "desist thy hot-dogging, grandstanding . . . and writing books on quarterbacking."

An equally vast, equally funny production number written by Joan Cushing is devoted to the mission of calling Walter Cronkite back from retirement. "Mr. Cronkite, just sitting at your desk/You look so Rockwellesque," the chorus intones. "You were there before the flood, although your name was sometimes Mudd."

Tipping the humor scales the other way is a long sketch on real-estate huckstering at a condominium complex called The 14th Street Mews. It is never clear who is the butt of this joke: the real-estate profession or 14th Street. And there are several gags and sketches to establish -- in case anyone was wondering -- that Iran students, the hostage crisis and the Ayatollah Khomeini have not yet, if they ever will, become ripe material for humor.

This revue also contains, strangely, no fewer than two sketches, revolving around the financial woes of the medical profession. In one, the Carter administration's medical cost-contained bill has passed -- with the result that your friendly neighborhood physician is employing second-hand tongued-degressors and an ape assistant named "Miss Simian." In a second, the concept of the malpractice suit is mocked by imagining such actions being filed against a waiter for putting sugar in a cup of coffee a customer wanted plain and against a prostitute for broadly speaking, failing to satisfy. w

What in the name of Hippocrates is going on here? Does the AMA have a piece of the show?

But in general, "Tongue in Cheek" is good medicine for a town under the grip.