THERE YOU go, putting your heart above your headboard again. Candlelight, roses, champagne -- you're launching a full-scale campaign to conquer a standoffish Valentine over dinner Saturday, right? A last-ditch effort?

Well, hit the red alert when you plot the menu. This is V-Day on the romantic beachhead, and if you bomb, it's Hiroshima, mon amour.

Some foods are considered aphrodisiacs because they are psychologically suggestive: oysters, asparagus, bananas, ginseng, rhino horn (powdered and hard to find these days). Eggs, caviar and mountain oysters are supposed to transmit virility. Game is served to unleash the animal within; venison and rabbit are particularly associated with Aphrodite.

Seafood has been revered for thousands of years. The Greeks, Carthaginians, Romans, etc. mixed it into the myth about Aphrodite being born from the foam of the sea, and in some ancient cults, priests were forbidden to eat fish because of its salacious influence. The pufu, a puffer fish found in the China Sea, is the Japanese equivalent of Spanish fly (it can also be poisonous if not prepared by an expert).

As a matter of fact, oysters, the favorite of Casanova, Madame du Barry, Don Juan and others, are rich in iodine and may stimulate the thyroid. Campagnes, and other wines which undergo a second fermentation, develop a stimulant called tyramine. Tyramine is also present in aged cheeses such as bleu and brie.

Chocolate contains theobromine, which is similar to caffeine but less harsh. Yams contain substances similar to cortisone and estrogen; sarsaparilla tea has elements similar to progesterone and testosterone.

So stack the odds with caviar or oysters; lobster in champagne sauce; medallions of venison and asparagus spears (small, distinct portions of each; you don't want to feel heavy and sated). Finish with fine chocolate or, for a final touch, chocolate-dipped bananas. (Peel the banana, wrap in foil and freeze; dip in melted semisweet chocolate and freeze again. These cannot be eaten with a straight face.) LASCIVIOUS LOBSTER (2 servings) 2 1 to 1 1/4 pound lobsters, slightly steamed and cooled 5 tablespoons softened butter Sauce: Oil for frying 1 medium onion, diced 1 stalk celery with leaves, diced 1 carrot, diced 1/3 cup cognac 1/2 cup fish stock or chicken broth 1 1/2 cups champagne 1 teaspoon dried tarragon 1 teaspoon basil 1 clove garlic, minced Salt and white pepper to taste Hot pepper sauce to taste 1 tablespoon flour

Open the lobster tail carefully, cut the meat into chunks and set aside. Cut open the abdomen and discard the intestinal vein and sand sack. Scoop the green tomalley and coral into a sieve over a small bowl; rub through the sieve with 4 tablespoons of the softened butter and scrape the bottom of the screen. Cover and refrigerate.

Remove and shred the claw meat and refrigerate. Chop the rest of the lobster shells.

Film a large saucepan with oil and set over high heat. When very hot, add the chopped shells, stir and toss 2 to 3 minutes. Add onion, celery and carrot. Pour in cognac, ignite and let flame for 5 seconds, shaking the pan. Extinguish by adding stock and champagne. Add tarragon, basil and garlic, salt, pepper and hot pepper sauce to taste. Simmer until reduced to about a cup, strain and return to saucepan over a low flame.

Mash the remaining butter and flour into a paste and whisk into the lobster sauce for 2 to 3 minutes. Then whisk in the tomalley butter and add the shredded claw meat. Add the tail meat, stir a few seconds to heat through and serve over hot toast triangles.