Elk regalia.

Why, you wonder, would grown men and women be caught out of the house wearing these funny-looking hats and glittering collar-yokes that look heavy enough to bring a draft horse to its knees? Ah, that's only because you've never been washed in the blood of the secrets. Fraternity, to an outsider, is probably a little like faith. It seems inexplicable. You either have it or you don't. You're either in Elkdom or you're not.

"That one there would cost you maybe $100 for the basic stones and bars," a salesman says, hovering over a table of wondrous rhinestoned collars.

On up to what?

"You name it. It's like customizing a car: The only limit is your wallet and imagination."

By the way, what does that C.F.L.J.S. stand for?

"Oh, I could never tell you that."

This week the Sheraton Washington Hotel has turned into the Grand Lodge of black Elkdom. Never have so many antlers been seen in one building; possibly never have so many amiable people milled about a hotel lobby calling each other Brother This or Daughter That.

They are proud brothers and daughters of I.B.P.O.E. of W. -- the Improved Benevolent and Protective Order of Elks of the World. They are morticians and beauticians. They are lawyers and doctors and elevator operators and Bahamian straw workers. They've come, for their 83rd annual assembly, from places like Hercules Lodge No. 90 (East St. Louis) and Henry Hampton No. 782 (Tupelo, Miss.) and Columbia No. 45 (Third St. N.W., Washington, D.C.).

They are probably the largest black fraternal organization in the world. Nobody seems to have exact records of these things, but perhaps only the Baptist Convention is bigger. This year an estimated 30,000 people (and a hoped-for 4,000 Elk delegates) have convened out of a total worldwide black Elk membership of 450,000. This "quiet" organization, never at the forefront of civil rights, but never a laggard, either, got started in Cincinnati in 1898 when Benjamin Franklin Howard applied to the local white Elks lodge and got turned down. Howard became the first Grand Exalted Ruler of Cincinnati Lodge No. 1. But the black Elks have no racial charters; in fact, they have some white members.

They've come to Washington to fraternize and to bulge their waistlines; to stay up all night drinking each other's booze; to comb the city in waves of unmistakable fancy fez dress.

They are staging grand balls and bathing beauty contests and parades and oratorical contests. (An aspiring young orator named Martin Luther King Jr. won the contest years ago and got himself a scholarship to college.) But they've also come to their nation's capital to decry Reagan economics; to seek strength and inspiration in numbers; to climb high, as one of their evangelistic guest speakers told them Monday, "in the mountains of God's purpose."

"I see the stars/I hear the roll of thunder," a man sang one afternoon at the civil liberties session. He was one of the convention's official Songbirds. The man was big enough to be an Oakland Raider and was backed up by a soft churchy organ of amazing grace. Heads swayed in the fluorescent light. Buxom ladies in nurse's white and stainless gloves chorused "Amen." The organist played an aching "Auld Lang Syne" and "Battle Hymn of the Republic," and it was easy to think of places named Selma and Montgomery and to feel the light, fevered, goose-bumped memories of a long, long-dead time running up your arm.

Black Elks form a microcosm of black life, it is said. Perhaps, also, this is true: Inside those secret lodges and temples, many of them in the heart of crumbling cities, are found a status and pride all but denied outside. The status and pride are borne of a ritual and fellowship that merely seem absurd to the uninitiated, no more absurd, perhaps, than what one would find at the weekly meetings of Rotarians, Eagles, Lions or Moose.

An Elk in full cry and dress is something to behold. This year, suppliers of Elk regalia were offering fezzes with regular rhinestones (imported rose montee) or white cup stones (rhinestones set in white plastic base). You could get a tassel of lustrous rayon or rayon chainette -- your choice. Engravers and embroiderers stood by to do lettering and pressing. The LK-5 Imperial Crown was going for $59, basic, while the LK-6 Exalted Crown went for $72.

At a booth selling music boxes there was a sign that said: "Ask about our Elk telephone stands."

The things one heard.

"I'm not sure how big our parade will be this year, Brother Watson."

"Bigger, bigger than last year, Brother Rush."

(A convention official estimated 15,000 marchers.)

A man stood smoking a fat rope of cigar behind the Tara Gem booth in the hotel's exhibit hall. Tara Gems are out of Mableton, Ga., a suburb of Atlanta.

"We took our logo from 'Gone With the Wind,' " the man said. "Right out there in Jonesboro. We used to hit the Baptists every year, too. But that's gone now."

"Gone?"

"Gone. The head of the Baptists threw out all the booths. Actually, the exhibits here are a little down this year. That's because the Shriners are holding their meet in Denver this week."

William Rush has been in Elkdom for half a century. He is a Past Grand Exalted Ruler. "Fifty-two years, I'm one of the old boys," he says proudly. "Been married 50 years, too. No, 51. We grew up in it together." Rush, who headed this year's executive committee, has the Southern Valet Shop on Florida Ave. He is a 33rd-degree Mason as well as a Shriner. No sense asking him why he's such a joiner. He just loves it. "We've been through many battles. It's a little like trying to get up a hill. You go up, and then you come back down a little. I've got a nonpaying job. I figure it costs me $5,000 a year to be an Elk." When he wasn't in fez, Rush could be seen on the convention floor in a splendiferous Stetson.

Marion Barry addressed the convention Monday afternoon. "You come at a time . . . at a time when Martin Luther King Jr. would describe this hour as midnight," the mayor said, sounding faintly like an old-time gospel preacher. He mentioned his Memphis boyhood. He said we "cannot forget the bridges that brought us over." And then he said, "Any race of people that can survive slavery, as black people have done, can survive anything, including Ronald Reagan." He said he wanted to stay, but he had business and, besides, there was a campaign on. He floated out on strains of "Battle Hymn of the Republic."

This year's convention was more historic than usual, in that the torch of leadership was passed from the Hon. Hobson R. Reynolds, Grand Exalted Ruler for the past 22 years, to Donald P. Wilson, who may lead the group into the new century. Hobson Reynolds, who served two terms in the Pennsylvania legislature and introduced the first equal rights law in the state, is a civil rights leader known throughout black America. His was never the loud rhetoric of CORE or even SCLC. "Not hollering about ourselves was the way to get work done," he once told an interviewer. Reynolds is infirm now and had to be helped to the podium. A smooth white knob hummed behind his left ear: He doesn't hear well anymore.

Congressman Walter Fauntroy was presented the group's Lovejoy Award. He came in a rep tie and a mortgage banker's suit. But, he, too, got fevered with the Word. When he was a boy, Fauntroy thought he had won an Elk oratorical contest, only to come in second. Joe Louis understood something about life, he said: "Don't take no chance on no decision -- knock them out." Then the congressman did a song. It was about never growing old. "There's a land where we'll never grow old," he warbled, sweet as a canary.

"Sing that song, Brother," somebody called.

"Never grow old," Fauntroy sang.

A line of soft "nevers" rippled through the house.