Parboil one and one-half pints oysters, drain, cool, and remove tough muscles. Cut three grape fruits in halves crosswise, remove pulp, and drain. Mix oysters with pulp, and season with six tablespoons tomato catsup, four tablespoons grape fruit juice, one tablespoon Worcestershire Sauce, eight drops Tabasco sauce, and one-half teaspoon salt. Refill grape fruit skins with mixture, and garnish with curled celery.