I KNOW WHY Janus had two heads -- the better to dodge his creditors.

After the New Year's hangover has dissipated comes the real financial headache. Eleven pipers piping want to be paid at once, and American Express knows you only too well.

Entertaining in January requires imagination and discretion. We're talking cheap thrills here, but with flair: No skulking around. If you can't condescend gracefully, you're better off declining to receive.

Affect informailty in clothing and atmosphere. Wear your jogging suit, or paint the front of an old sweatshirt (this is bas chic, if you can carry it off). Wine should be served from a jug in mismatched glasses. Don't laugh: It works for A.V.'s.

If you're out of firewood, spend an hour scavenging for wood and chop up the Christmas tree. Cut heavy cardboard boxes into small squares for kindling. Roll old newspapers tightly, soak them in water and dry them out for logs. Say you made a New Year's resolution to clean the basement, or just start the fire beforehand.

Concoct a casual scenario in advance. Invite her to watch the Super Bowl over cheese-topped chili and beer. Nosh on a bag of Doritos and a bottle of hot sauce.

Have a junk food festival. His favorite, your favorite and perhaps a complement: one bag of something sweet to two salty crunchies. Do a Bob's Famous fete -- two quarts of ice cream and a variety of toppings. Chee-tos are delightful with slices of Danish ham cut into strips and rolled up with toothpicks. A one-pound bag of peanut M&M's will get you through a long stretch of backgammon.

Rice, especially long-grain mixed with wild, turns a few leftover mushrooms and a piece of chicken or ham and roast beef scraps into first-rate pilaf. Get a bottle of small boiled onions and use the onion water and wine or vermouth to make up the necessary liquid. (The basic pilaf principle is simple: Saute the rice grains with basil and parsley in melted butter until opaque, then add the liquid a little at a time and let it simmer away. The onions and mushrooms can go in early, meat scraps about halfway. Serve with a dollop of sour cream on top if you like, and a salad.)

Whimsey is cheap, fortunately. Invite him over to watch a late movie some night over an appropriate meal. Try to pick an old flick about a semi-seedy private eye, or "Angels in the Outfield" or "The Good Earth" and whip up some homemade hash or hotdogs or a quick stir-fry and rice. Avoid "Tom Jones," "Animal House" and "Someone Is Killing the Great Chefs of Europe."

Or stretch the budget by making it go farther. For example, buy the sirloin half of a leg of lamb and ask the butcher to bone and cube it for you. Separate the meat into three freezer bags, and it will be enough for one curry, one shish kebob and one ragout; or grind it for stuffed zucchini or little rich meatballs. (This is trickier if you tend to entertain the same person all the time).

If you have fruit and rabbit food left over from the holidays, cube and saute a couple of pieces of chicken, an apple, a zuke or yellow squash, celery, onions and mushrooms with some yogurt or sour cream and a healthy dose of curry powder and lemon.

You can spoof the good life with domestic champagne (drink it very cold or crush a few berries into it to disguise it) and lumpfish caviar with cream cheese or sour cream on crackers. You could add onion or potato soup. The oysters down on Maine Avenue are delicious now; warm them in the oven till they just begin to relax, then dress with a squeeze of lemon and a grind of black pepper.

Make a fish chowder or cioppino with a few pieces of fish, celery, onions, potatoes, tomatoes. Most fish markets will give you heads and scraps for the stock.

Or make one last political statement: Salute the new president with macaroni and cheese and jelly beans or stir the emergency jar of peanut butter into soup. Cheapie Cioppino 2 tablespoons butter 1 medium onion, chopped 2 scallions, chopped 2 cloves garlic, minced 1 cup fish stock, clam juice or water 1/2 to 3/4 cup red wine or dry vermouth 1/4 teaspoon salt Dash of white pepper 2 drops hot pepper sauce 1/2 teaspoon basil 1/4 teaspoon marjoram 1/2 bay leaf 1 potato, chopped 1 carrot, sliced 1 small can plum tomatoes, chopped, with their juice 1 medium zucchini, chopped 6 or more mushrooms, quartered 8 ounces fish (cod, rockfish, sole, flounder, snapper) cut in bite-size pieces 1 tablespoon cornstarch (optional)

Melt butter in large saucepan. Cook onion, scallions and garlic until tender. Stir in stock and wine, salt, pepper, hot pepper sauce and herbs. Add potato, carrot, tomatoes and tomato jucie; bring to boil. Reduce heat, cover and simmer 10 minutes. Add zucchini and mushrooms; simmer 10 minutes more. Add fish and simmer 5 minutes or until fish flakes.

Use more wine for a thinner broth. To thicken, remove fish and vegetables, add a tablespoon cornstarch dissolved in 2 tablespoons water. Return fish and vegetables and heat through.