There was a story current in Washington a year or so ago of how one of the city's better-known law firms celebrated Christmas: They held a sit-down dinner, black-tie, please, for members of the firm. Husbands and wives were not invited.

The pomp fit the firm, but have other offices managed to match their Christmas party with their public image?

Does the International Apple Institute decorate its halls with pyramids of glowing Red Delicious, while baked Staymans bob around in bowls of Wassail? Does the Sugar Association break out in a rash of sugar plums and sugar canes, striped with red curant glaze? Does the Chocolate Manufacturers Association disappear in a sea of chocolate Santas? At the Association of Ice Cream Manufacturers is pistachio ice cream molded into Christmas trees around which cluster chubby, strawberry Santas?

No.

"We think about our product the rest of the year. At Christmas we think about Christmas," said one association employe, explaining that his group -- like many others asked -- holds their Christmas party at a restaurant.

Maybe the reason the office Christmas party is so maligned (barring the threat of scandal when a liquor-brave employe tells off the boss, or the boss, similarly emboldened, goes after his secretary) is that it's boring.

The large group meal in a nearby restaurant or the platter of fading cheeses accompained by slightly warm white wine . . . and for excitement, the same people you see the rest of the year.

Given the predictability of the guest list, the Christmas party at the office needs help. One way to spice it up is to adopt the customs of Mexico. oBy the time blindfolded employes have taken turns aiming swings at the pinata, all aggression should be gone. (Pinatas can be bought at Old Mexico, 1410 Wisconsin Ave. N.W., for $9, or at Iberian Imports, 225 N. Fairfax in Alexandria, for $8.50 or $16).

A Mexican meal can be put together out of the supermarket freezer; you can call around and find a Mexican restaurant to provide food; or you can bring your own fillings for store-bought tacos and tortillas. Guacamole is easily made and taco chips easily bought.

The pinata can be filled with appropriate gifts or office jokes (nice ones -- remember 'tis the season to be jolly), and if you really want to get into the spirit of a Mexican Christmas party, you can ask office cooks to prepare some traditional Meixcan sweets. Bunelos, little fried pastries, for which there's a recipe in Diana Kennedy's "The Cuisines of Mexico" (Harper & Row, $15.95), or capirotadas , a bread pudding you can make from the recipe in Kennedy's newest book, "Recipes From the Regional Cooks of Mexico" (Harper & Row, $12.95), or Elizabeth Lambert Ortiz' "The Books of Latin American Cooking" (Alfred A. Knopf, $15).

With the food serve Mexican beer, and, before guests depart, warm them up with cups of Mexican chocolate. It's a safer way of saying Merry Christmas to people you want to see tomorrow.