If you spot a procession of button-down types trotting down K Street with brown bags at mid-day, they're probably on their way to chow down with Jimmy Carter's former national security adviser, Zbigniew Brzezinski.

Every two weeks or so, Brzezinski gathers about a dozen friends and former staffers around a table at his downtown Washington office for a food and gabfest. He calls it The Z. B. Brown Bag Lunch. Logical topics on the table: gossip about where the old gang is now and much talk of Poland, Brzezinski's homeland. There's no mistaking Brzezinski's hardline on the military crackdown; he's branded Gen. Jaruzelski a "Polish quisling."

Brzezinski spends Monday and Tuesday in New York where he is a professor at Columbia University. The rest of the week is spent behind the locked door of his office on K Street, just down the hall from James Schlesinger and downstairs from Henry Kissinger's office-in-exile. (Brzezinski sniffs at reports of a rivalry with Kissinger; "We had breakfast shortly before he went to be operated on," says Brzezinski.)

Between lecturing at Georgetown University's Center for Strategic and International Studies, Brzezinski writes his memoirs and makes an occasional speaking appearance. He still has the brush haircut and rapid fire talk that led some in the Carter White House to nickname him "Woody Woodpecker."

After Carter lost his reelection effort, Brzezinski says he thought he'd "be frustrated and disappointed and life would be a letdown." But he says he likes his freedom. And at the Z. B. Brown Bag Lunch, the menu may only be sandwiches, but Brzezinski acts as if the world is still his oyster.