Suffering the slings and arrows of a little presidential outrage, House Speaker Thomas P. (Tip) O'Neill Jr. let loose with some righteous indignation of his own last night at a reception in Georgetown for some 200 Democratic Party stalwarts.

At the heart of O'Neill's pique was Ronald Reagan's accusation at his press conference earlier in the day that O'Neill resorted to "sheer demagoguery" when he said the president did not understand the working man.

"I'm surprised that the president of the United States would make a statement about the speaker like that," said O'Neill, employing the third person singular with regal detachment. "I trust in the future he'll have more respect for the title of speakership."

To those in town for the $1,000-a-plate Democratic Congressional Dinner tonight who hadn't seen O'Neill in several months, he seems almost a mere shadow of his former self."Gold," he confided, refusing to play the numbers game but looking very pleased indeed when someone speculated that he must have dropped at least 25 pounds.

What didn't please him was Reagan's lack of respect.

"I have too much respect for the speakership and the greatest respect for the president of the United States -- whoever holds the title. It's the office."

O'Neill claimed that what he actually had said about the working man was that people around Reagan "are not familiar with the problems of Middle America and the poor -- I always talk in the third person when I talk about the president because I have so much respect for the title."

Professing to have "great respect" for the people around the president who are self-made men (he cited Treasury Secretary Donald Regan, for example), O'Neill said they should nevertheless remember where they came from.

"The trouble is they associate so much with the wealthy that they only know the problems of the wealthy. They don't know the problems of Middle America, how Social Security or nutrition programs or student loans affect them. You just can't cut those budgets without it having a tremendous affect on the average American," said O'Neill.

Standing in the hot, crowded drawing room at historic Prospect House while Democratic Party heavyweights like the senators from Texas, Arizona, Kentucky, Ohio, South Carolina and New Jersey and the governors of Kentucky, New Jersey and Puerto Rico milled about in the background, O'Neill seemed to take exception to another Reagan remark about "trying to find out something about his [O'Neill's] background."

"You know, long ago I remember a conversation with President Truman," said O'Neill. "He said never talk about a family. You may talk about the individual in public life but never the family. So I'm talking about the policies he's creating. I would never attack the man."

Those policies came under a barrage of attack wherever Democrats assembled in Carol Shapiro's stately Federal brick home. Former HUD secretary Moon Landrieu, back at work in New Orleans real estate and law, worried that "we're facing a terrible crisis in housing, and much of what had been revitalized in cities has been cut.

Kentucky Gov. John Y. Brown, there with his wife, Phyllis George, said he was all for cutbacks: "I campaigned, like Reagan, that government should be run like a business -- but if people want to get rid of welfare, in order to do that you've got to provide jobs."

Nobody seemed very interested in weighty philosophical discussions about party disarrary or how to rebuild it. Reception host Robert Strauss made a stab at it when he said some people think the party needs new coalitions in order to develop new ideas, when actually it's new ideas that attract new coalitions.

"Matter of fact," said Strauss, warming up to the idea the more he thought about it, "maybe I'll try that out in my speech tomorrow night."

"The Harris poll is absolutely true. The Democrats would win the House if the election were this week," said Rep. Jack Brooks of Texas. "Of course the election's not going to be this week and the trouble is the Republicans are going to spend a hundred million dollars on those elections.