To be a Hungarian you have to be a bit of a dreamer and a bit of a realist and an over- achiever as both. The ideal is a cheerful cynic who is also a passionate believer, a prestidigitator who rejects the law of gravity, a mix of Don Quixote and Henry Kissinger. What is admired is the courage of your illusions. And sobriety is treason.

For some 500 people this Saturday night at the Capital Hilton, the gray Potomac will seem like the blue Danube, and the District of Columbia will be a Budapest that is not on the map any more. Six Gypsy musicians, said to be the best in the United States, will supply the melodies indispensable to such a class action of enchantment. And you don't have to be Hungarian to join in.

The Hungaria Ball -- Hungaria is Latin for Hungary -- is a time off from the real world with its income tax returns and Betamaxes, with its risks of RIF in Washington and the reality of the Red Army in Budapest. It is an occasion to forget and to remember: a time to ignore the present and to waltz back into the 19th century, so superior to the 20th in its passions and poses.

For lissome Katalin Teleki, who fled Hungary in 1956 as a teenager, this Saturday's will be the 18th Hungaria Ball in Washington -- she has faithfully attended all but one of them. The ball is the high point of her year, "a once-a-year outing into a traditional way of life, to dance as my parents and grandparents did." For the rest of the time, Katalin is an announcer at the Voice of America, and her husband Charles, also Hungarian-born, is a scientist, a consulting engineer with NASA. But for at least this one evening, Katalin is known as a descendant of Huba, one of the legendary chieftains who conquered Hungary in the ninth century; and Charles is Count Teleki, from a family of landowners and cabinet members.

She has a girlish figure and violet-blue eyes; he has a sharp tongue and a rakish grin. Both are terrific dancers.

Watching them and listening to Gypsy music alternately tearful and joyous, you wish you were in love with Katalin or Charles. Or you wish you were in love.

The annual Hungaria ball is the gala night of the Washington-area Hungarian community, estimated at l0,000 souls. Its official function is twofold: to raise funds for a nondenominational Hungarian chapel near Berkeley Springs, West Virginia and to present debutantes.

Nearly all the debutantes are born and raised in this country, and most of them are dragged kicking and screaming into this act of tuxedoed madness and high Hungarian pretension. But usually the proud father wins out. Just for Dad's sake, Judy who was born Jutka will learn to dance the cs,ard,as, the waltz and the polka, and she will wear that low-cut $500 silk number from I. Magnin or the lacy nonsense crazy Great Aunt Marishka toiled over for weeks. And when it's all over, Judy admits that she had a good time, but, oh no, never again, once is enough for a lifetime.

Or at least never until next year.

HUNGARIA BALL -- Saturday at 7:30 at Capital Hilton; $45 including dinner, $20 for dance only. Call Ms. Gyorik, 234-8021.