What if you gave a press conference and nobody came? It has happened before in Washington, where free booze, food and even a small circus sometimes aren't enough to attract press coverage if the subject at hand isn't deemed interesting. Faced with these depressing facts of public relations in the big city, World Airways took a new approach to announce resumption of its cut-rate transcontinental fares after a four-month strike: Washington PR man David Apter hit upon the idea of a do-it-yourself press conference. About 600 boxes with a tape cassette message, Macadamia nuts, airline-sized bottles of vodka, bourbon and chablis, and even a "Hello, my name is -- " lapel label were delivered to reporters in the major markets served by World Airways -- Washington, New York, Los Angeles, San Francisco and Honolulu. The recipients were encouraged to pour themselves a drink, munch some nuts and listen to the taped spiel for World's $202, one-way, coast-to-coast cash fare. Each kit cost about $7 to produce, according to Apter. Did it work? A San Francisco newspaper wrote a front page story about the unique pitch. The Los Angeles Times headlined its article "World Airways Tries Gimmick -- It Works, Hic." And in preceding paragraphs, you've read the message World Airways wanted to bring to your attention.