Lunging over the pigeon pie at the Moroccan Embassy last night, Sen. Charles Percy (R-Ill.) asked one of the hot questions of the evening. "Hey," he said to James Rentschler of the National Security Council, "what do you know about what's happening in Mecca?"

"The situation," replied Rentschler, "is very cloudy." And with that, everybody -- at the "pineapple table," anyway -- abandoned talk of international crises and settled down to real estate, the kids and the fact that Upper Volta is not only a lousy place to live but a worse place to visit. (The assessment of Rentschler, who did both.)

But during cocktails at the small embassy party for Angier Biddle Duke, the former protocol chief and new U.S. Ambassador to Morocco, the 50-odd guests gathered in a rust-carpeted, chandaliered living room and exchanged information about what they knew of a reported takeover of the mosque in Mecca.

"It sounds very serious," said Stefan Groueff of the Embassy of Oman. "It is perhaps inspired by the Khomeini people."

"They are the same kind of people," agreed Ali Bengalloun, the ambassador from Morrocco who, like everybody else, buzzed about a situation he had only heard about via Walter Cronkite and the seven o'clock news.

The dinner party, in addition to being a who's-got-the-latest-on-the-crisis affair, also served as the social reintroduction of the Dukes to Washington. They've been out of things in New York or London since the late '60s, and last night got a good look at cohorts they haven't seen in years.

Duke, in fact, stood off on the side and assessed the old faces. "Sen. Cooper (former Sen. John Sherman Cooper) looks just the same," he said. "Joe Tydings looks younger than ever. The point is, time has stood still. Livingston Biddle looks a lot thinner; I won't say careworn, but he looks very hardworking. I wonder how I look to them?"

Well, they'd better look fast.Assuming Duke's confirmed by the Senate, he takes off for Morocco next month. Once there, he'll be in the midst of a war with the Polisario Front guerillas in the Western Sahara.

The party attracted some respectable Washington all-stars: Supreme Court Justices Byron White and Potter Stewart, former ambassador Averell Harriman, Senators Jacob Javits (R-N.Y.) and Claiborne Pell (D-R.I.), protocol chief Abelardo Valdez and Sol Linowitz, soon to be Mideast negotiator.

The party, because it was so small, created some interesting pairings during the cocktail hour. Averell Harriman chatted with Sen. Percy's wife on a couch, and Linowitz, over near a window, murmured fast and furiously with Justice White.

He'll also be pushing for Senate approval of a U.S. arms sale to Morocco, a sale he expects to be finalized after the first of next year.

"We hope that then, Morocco will be able to go the negotiating table from a position of strength," he said. "We hope it will contribute to the stability of the area." But others, including Rep. Stephen Solarz (D-N.Y.) have argued the sale will prolong the war rather than shorten it.

Carter, Linowitz said, "is trying very hard to deal with the most agonizing problem we've ever had." Linowitz was referring to Iran and how it affects the Mideast negotiations. "It isn't good, and that's a fact," he said.

Linowitz clearly didn't enjoy answering questions about a job he hasn't assumed yet. White was sympathetic and tried to fill Linowitz's mouth with other things. "Would you like to chomp on some caviar?" White asked Linowitz.

The cocktails were easy. The dinner, which was Morraccan, wasn't. Or at least it wasn't for a good many Americans, who first knocked their knees on the low, fruit-named tables and then stared with puzzlement at the first course.

This was a giant plate of bestilla, or pigeon pie, which would have just sat in the middle of at least one table had not a friendly Morroccan begun passing it around.

Next came the lamb course. The Morroccans just dug in with their hands, and the Americans, after some genteel hesitation, did the same.

"Well, I guess we should just jump right in," said publisher Walter Ridder. "I don't know whether it's in or it's out to eat with my fingers."