It was George Bush's first taste of presidency.

As President Reagan looked on, Bush accepted the presidential nomination of the Alfalfa Club, Washington's boys' club for the biggest, at their annual men-only gathering Saturday night.

A number of the 670 guests at the Capital Hilton said Bush did a fine job. But the most memorable joke of the evening came from the Great Communicator himself.

As recalled by Jack Valenti, president of the Motion Picture Association of America, it went this way: "Reagan said he knows his place in history is secure. In the Cabinet Room, above his chair, is a plaque that says, 'Ronald Reagan slept here.' "

Rep. Jack Kemp (R-N.Y.) called it "the hit of the affair." And how did Bush do?

"He's shown a firm grasp of his responsibilities," said former attorney general Elliot Richardson.

Did he advance any new ideas for the Alfalfa platform?

"No original ones, but then no Alfalfa Club president should."

And as a speechmaker? Any memorable quips?

"No. Well, he may have, but if he did I didn't remember them," finished Richardson.

The dinner was to start at 7 p.m., but as early as 5 p.m., the private pre-Alfalfa parties began, given throughout the hotel by various corporations. Until the event's midnight wrap-up, the lobby was filled with curious onlookers expecting to see the president. But he came up the back elevator, as did the vice president and a number of other government bigwigs and captains of industry invited to the black-tie dinner.

There was little danger that Reagan would mind seeing his vice president be made president for a night. Said Henry Kissinger: "It's the state of things for a vice president to let himself be made president."

But a few felt that last year's Alfalfa president, Sen. Sam Nunn (D-Ga.), showed the most promise for the 1988 presidential election. "If you ask me," said former defense secretary Melvin Laird, "Nunn's probably the toughest contender."

Among the highlights of Nunn's remarks:

* "I hope that Sen. Jesse Helms will buy CBS in time to pay Westmoreland's judgment of $125 million." Retired general William Westmoreland, an Alfalfan, was there to appreciate that.

* On winning the Alfalfa presidency: "Getting this job was the political equivalent of getting a kidney transplant from a donor who was a bed-wetter."

The 72-year old Alfalfa Club, named for the plant that sends its roots deepest for liquid refreshment, meets just once a year for surf 'n' turf 'n' jokes.

"We meet to do nothing and do it well," as Patrick Hayes, director emeritus of the Washington Performing Arts Society, put it.

"I'm pretty unclear about the whole thing," said former Treasury secretary Joseph W. Barr, trying to explain the longevity of the society. "Maybe that's the reason it operates so well."

Another reason why the evening operated so well was the presence of seven tuxedoed young women with last decade's Farrah Fawcett hairdos helping the many white-haired Alfalfans up the stairs. They also did a fine job of shielding the men from photographers and reporters, who were allowed no closer to the second-floor ballroom than the hotel lobby.

"We're supposed to forget everything as soon as we leave the room," said David Lloyd Kreeger, apologizing for his after-dinner reticence. "But it was a very happy affair."

And how did Carmen Kreeger spend her Saturday night?

"My wife spent the evening at the movies with the grandchildren," said Kreeger.

"And missing us," piped in son Peter.

"It was the time of our lives," said the new French ambassador to the United States, Emmanuel de Margerie, who was seated between Defense Secretary Caspar Weinberger and outgoing Interior Secretary William P. Clark. Of his dinner companions, de Margerie said, "It was a great lesson in American life."

Said Saudi Ambassador Prince Bandar bin Sultan: "I thought it was marvelous. We saw tonight one of your greatest assets -- the ability to laugh at yourselves. I did."

Among the other guests upholding the Alfalfans' longstanding, if anachronistic, tradition, were Attorney General William French Smith; attorney Edward Bennett Williams; Federal Reserve Chairman Paul Volcker ("They didn't say anything about the Federal Reserve, so that's good"); former Missouri congressman James Symington ("The night was absolutely classic"); and Chief Justice Warren E. Burger (who signed autographs for a couple of adolescent admirers on his way out).

Among the congressional contingent: Sen. Ernest F. Hollings (D-S.C.), Bush's vice president for the night; Sen. John Warner, who politicked outside, shaking hands with elderly female admirers; Sen. Barry Goldwater (R-Ariz.); Sen. Pete Domenici (R-N.M.); Sen. Paul Laxalt (R-Nev.) ("Bush will make a great president"); former Illinois senator Charles Percy; Sen. Charles McC. Mathias (R-Md.), who found the evening "very fun and lighthearted"; and Sen. Mark Hatfield (R-Ore.) (Bush "has been in a good job training program.").

Autograph hunters also pounced on former Senate majority leader Howard Baker, addressing him as "Mr. President."

"Keep that thought fixed in your mind," laughed Baker, who hasn't kept his presidential aspirations a secret.

Did he think Bush would be a tough contender in 1988?

"Sure will be."

But in Baker's book, that's no reason to get competitive about it. "George and I are good friends, have been for a long time and will stay that way."