It was late on a Sunday night in the bowels of the Commerce Department, and an unnamed International Trade Administration investigator was feeling slightly punchy from the pressure of working on a spate of unfair-trade complaints filed by the domestic textile industry against 13 Third World nations.

In a spirit of lightheaded fun, according to Commerce sources, he drafted a parody of the questionnaires going out to the countries accused of illegally subsidizing textile exports to the United States.

The questionnaire was addressed to "H.E. Baron Ottokar von Przemysl," commercial counselor of the "Grand Duchy of Plecszy-Gladz."

For the most part, it makes pretty dry reading. But on Page 5, the ITA official listed the subsidies that textile producers in Plecszy-Gladz were accused of enjoying:

1. Industrial Baronies and Fiefdoms;

2. Provision of indentured serfs to the textile industry at the expense of the Grand-Ducal exchequer;

3. H.R.H. the Grand Duchess' redecorating of the Grand-Ducal palace with bright brocades and designer damasks at inflated prices in order to boost the carriage trade;

4. Outfitting of the H.R.H. the Grand Duke's Own Regiment of Hussars with tasteful tunics of Teal and Taupe at huge cost overruns; and

5. Free food and fuel provided to families of impoverished weavers by His Eminence the Cardinal-Archbishop of Plecs.

Although meant for internal consumption only, the fake questionnaire quickly spread through trade circles in Washington, and top ITA officials became concerned that the parody would be taken as a sign of American insensitivity to the problems of Third World nations. There were even fears that it would be used to attack the United States during meetings of the Geneva-based General Agreement on Tariffs and Trade (GATT).

ITA officials scurried around town, trying to retrieve all the copies, then reportedly ran them through a shredder to make sure the parody was lost to posterity.

A sampling of diplomats from the 13 nations hit by the industry complaints showed the agency's fears to be unfounded. Most of them diplomatically professed never to have seen the parody and asked for copies. Those who admitted seeing the fake questionnaire said they found it amusing.

The textile industry, meanwhile, is upset at the unusually caustic tone of the Commerce Department news release announcing that it would investigate the complaints against the 13 nations. Industry lawyers reportedly are drafting complaints to the department.

To whom they will complain is unclear, however, since Commerce Secretary Malcolm Baldrige personally added the phrase that pointed out that imports from the 13 countries amount to only 3.7 percent of the U.S. market.

The textile cases are shaping up as a bonanza for Washington lawyers who specialize in trade issues. They have been actively soliciting the 13 Third World countries, quoting fees as high as $200,000 for a case. The average was around $100,000.

That means the benefits to Washington lawyers will amount to more than $1 million. And that doesn't count the money that the American Textile Manufacturers Institute spent on legal fees to prepare the complaints. GOING, GOING, GUNN . . .

It wasn't too long ago that White House aide Wendell Willkie Gunn was being introduced in trade circles as the new assistant secretary of Commerce for trade administration, replacing Lawrence J. Brady, who resigned. But Gunn's nomination got tangled in politics, as some Republicans thought he favored export promotion at the expense of security controls on overseas sales. He was considered by some as tainted by past ties to Pepsi-Cola Corp., whose chairman, Donald M. Kendall, openly attacks government security concerns on foreign sales.

Gunn finally got tired of waiting and left the White House staff. His place there has been taken by Michael A. Driggs, who had been deputy assistant secretary of Commerce for automotive industry affairs.