There are two requirements for a Good Washington Joke: Make it at the expense of a very powerful person and give it a raunchy spin.

"I don't know if you've heard about the religious conversion at the White House," Rep. Lynn Martin (R-Ill.) told the crowd at last night's Washington Press Club Foundation Salute to Congress. "It's Don Regan. He's leaving to be a cardinal. For most of us it is a relief to know we will now only have to kiss his ring."

Martin managed to get the most gut-level laughs at the dinner, where six members of Congress attempted to be funny. The annual event brings together the congressional, administration and journalistic pantheons, and the point is, as foundation President Marlane Liddell put it, "to find our leaders human, and to laugh at ourselves."

There were the obligatory John Riggins jokes. At last year's dinner, Riggins told Supreme Court Justice Sandra Day O'Connor, "Loosen up, Sandy baby!" and was later seen sleeping under his table.

Last night, after expressing his surprise at being invited to speak, Sen. Charles Grassley (R-Iowa) told the 900 guests, who had paid $100 each, "You got so many headlines from John Riggins last year I thought you'd invited me to put even more people to sleep."

Riggins himself attended last night's event.

"Did you see him?" one member of the foundation whispered to another excitedly.

"It's a success!" replied the other.

Riggins was not as voluble, at least not to the press.

"I see you got your notebook," he said, turning his back. "I ain't working tonight."

Gramm-Rudman-Hollings was also a popular subject.

Jokester Sen. Phil Gramm (R-Tex.) denied that his budget-slashing creation has earned him the hatred of the American people.

"The people of America love me," he said. "They're always showering me with gifts. The senior citizens of the country got together last week to buy me an artificial heart."

Laughter.

"I've got a liberal's heart . . ."

Dramatic pause.

"I keep it in a quart jar on my desk."

Earlier in the evening, the journalists and their sources/guests gathered for drinks around a DeLorean, which several guests touched carefully and a few even ventured to enter. The car, lent by its owner, Mark Sheftell ("People have offered me companies for it," he said) was there to support the night's theme, "Back to the Future," taken from the succesful movie in which a DeLorean plays a major part. There were film clips from the movie, during which waiters stumbled to distribute the coffee, and food with names like "Thyme and Tide Chowder" and "Destiny Decaf."

The other speakers enjoined to speak about the past and future at the Sheraton Washington were Rep. Jack Kemp (R-N.Y.), Rep. Bob Edgar (D-Pa.) and House Minority Leader Robert Michel (R-Ill.). CBS congressional correspondent Phil Jones served as master of ceremonies. Swirling by them at the reception were Defense Secretary Caspar Weinberger, Office of Management and Budget Director James Miller, Chairman of the Federal Reserve Board Paul Volker, NBC's Roger Mudd, ABC's Sam Donaldson and assorted congresspeople and presslings.

Attorney General Edwin Meese was looking particularly happy as he laughed with his host, Ben Shore of Copley News Service.

"Pleasure!" Meese said of the purpose of the evening. "Totally pleasure. These are all my friends."

Shore said such an evening, when reporters wine and dine sources and subjects, "makes a lot of the professional contact a lot easier."

Meese laughed and pointed at Shore's tuxedo shirt.

"It's the tape recorder in his second button that records the whole thing!" he said.

There was much laughter.

Earlier in the day, there had been some misgivings about laughing at all.

"I think we all had concerns about whether or not it would be the right thing to do because the nation is in this period of mourning," said Jones, little more than a day after seven Americans died in the space shuttle explosion. As the afternoon wound on, some of the participants clearly felt uncertain about how the event should be handled.

Foundation members said that in light of President Reagan's remark yesterday that "life has to go on," the dinner would also go on. The newly formed foundation, created when the Washington Press Club and the National Press Club merged last year, will "advance journalistic professionalism." A committee is now deciding how the foundation's money will be used.

But several hours before the dinner, one speaker, Rep. Barbara Mikulski (D-Md.), decided not to attend.

Mikulski's press secretary James Abbott said, "She just feels if the president had gotten shot yesterday, or it was the day after President Kennedy died, we would not have gone. She doesn't want to make a big deal out of it, but she's just not in the mood to make jokes tonight. Some people are doing it with President Reagan's words in mind, that life must go on. That's fine. She's not talking about those who are doing it. She just herself feels she doesn't want to do it tonight."

Others felt differently.

"Had it been last night, it would have been impossible," said Beverly Hubble, Grassley's press secretary, of the dinner. "Not that the loss of life is any less horrible 24 hours later, but in some point things have to return to normal."

Kemp planned to arrive with a speech, but to "be prepared to do whatever the will of the majority of the participants is," said his press secretary, John Buckley.

Kemp did refer to the shuttle accident in between jokes. Liddell also spoke about it and asked for a moment of silence after the trooping of the colors.

Earlier in the day Jones said, "I think there is a great deal of thought being given to the sensitivity of the times. I'm making note of it at the beginning of my comments. 'We do not gather here tonight unmindful of the tragedy' -- and with that, try to make the transition."

And how would he do that?

"With a long, deep, silent pause. There is no easy transition to it."

But in the end, the evening seemed little different from any other such evening. Everyone made a funny, or not-so-funny speech, everyone mingled and table-hopped and griped because the whole thing went on too long, and then everyone went home.