What impressed some people was how cool Ali Ahmed Houderi, chief of Libya's People's Bureau, had played it -- although watching him last night in the hot glare of television lights, "cool" wasn't exactly the word that came to mind.

"It's important that a small country like Libya plays it cool and that a big country like the United States sometimes play it hot," said Arab League Ambassador Clovis Maksoud.

The Libyans, whom the State Department last week ordered to close their mission and leave the United States, did it about as coolly as anybody could by tossing themselves a lavish farewell party in the Madison Hotel last night. In less than 24 hours they rounded up about 300 of their closest American and foreign friends, many of them diplomats, some of them lobbyists, a few of them journalists.

"We wanted to say goodbye to our friends because we are going to miss them very much," said Houderi who, with his colleagues from the People's Bureau of the Socialist People's Libyan Arab Jamahiriya, formerly known as the Libyan Embassy, must leave the country by midnight tonight.

Houderi said he had been "surprised and shocked" last week to arrive at the State Department and be handed a note informing him and his 26-member staff that they were being expelled.

"They accused us of exporting revolution and not abiding by international conduct, but that's just ridiculous," said Houderi between handshakes with representatives of such countries as India, Pakistan, Grenada, Zimbabwe, Algeria and several of the 21 nations making up the Arab League.

Houderi said he didn't know what his country will do about its oil exports to the United States, which gets between 10 and 12 percent of its oil from Libya. "We will make a full evaluation of the economic and political situation and we will make a decision immediately after we get there." Houderi said nothing will happen to the 2,000 Americans living in Libya. "They will be safe and welcome and can continue going about their business, as I hope our students can in this country."

When former South Dakota senator James Abourezk, now a Washington attorney specializing in Middle East affairs, turned up, Houeri teased that "this time we're going to change places. We're going to be the super power, and you're going to play another role."

Abourezk said it was "very puzzling" that the Reagan administration had decided to throw out the Libyans -- unless the speculation about an oil glut happened to be true because, of course, "they don't want too much oil in this country."

As for the Libyans being terrorists, Abourezk said it raised the question, what is a terrorist? "Somebody who kills civilians? Then in that case there are a lot of terrorists in the world. Let's cut off a lot of countries, Chile and Israel for example. They're sending people out to kill other people. So let's be balanced."

Former Arkansas senator J. William Fullbright, also a Washington attorney, said he didn't approve of the expulsion or the "long-term treatment of Libya or other countries in the area that goes back 10 to 15 years. This is a culmination, but that's the way big arrogant countries act."

Is the United States a big arrogant country, Fullbright was asked.

"Sure as hell is," he thundered.

The Arab League's Maksoud said lots of people have been called terrorists "and have become prime ministers, like in Zimbabwe, for example. There was even a time when George Washington was being called a terrorist by the British."

Maksoud said the new administration "must appreciate and be sensitized to Third World aspirations, which might at times not be very similar to Western terms . . . Diplomatic relations shouldn't be conditioned on the approval of each other's policies but the vehicle by which one reduces the problems that arise from these differences and make them manageable."

Bars were stocked with fruit juice and soft drinks, but the buffet table offered guests a veritable binge in Middle Eastern dishes. Coming and going were diplomaats and representatives of Third World countries and movements like Cubs and the PLO. Also there was the Rev. Douglas Moore, former D.C. councilman, expressing outrage that his Libyan friends were being expelled.

"What kind of an administration is it when you have a man like Joe [sic] Clark who is No. 2 in the State Department and he doesn't even know who people are?"