One man put it bluntly: "Anybody who would defend the use of that awful phrase 'have a nice day' would defend anything."

Thus encouraged, I hereby undertake a defense of that bane of Washington cocktail parties, "And what do you do?"

It is no easy assignment, I grant you. The innocent-by-reason-of-innocuousness defense -- which works for "h.a.n.d.," doesn't work for "what-do- you-do." It is innocuous, of course, but you'd never convince a Washington jury. Washingtonians, especially those who don't do anything particularly interesting, see it as affront. "People who ask what you do are trying to find out whether you are worth talking to, and I resent it," one woman told me. Her attitude is fairly typical. It is also wrong.

Her mistake stems from a misunderstanding of the nature of the Washington cocktail party. She perceives "party" in the non-Washington, dictionary sense: "a gathering for social entertainment, or the entertainment itself."

Parties, in that sense, tend to be gatherings of friends, come together to have a good time. Back where you come from, friends know what you do, and so there is no need to ask. If you are the outsider at a non-Washington gathering of long-time acquaintances, the usual question is: "Where are you from?" There's nothing offensive about that one (unless you happen to be from someplace dreadful, like Philadelphia, Newport, Ky., or New Jersey). It is seen for what it is: an attempt to get to know you.

Washington cocktail parties have nothing to do with "social entertainment." Their purpose is not fun but work. People who give them hope to win support -- or at least a measure of neutrality -- for their policies and programs, their charities, their governments or their consultancies. Most of the guests are strangers, which means that for a dreadful hour or two you are required to circulate around the room making small talk with people you don't know.

The problem is, what do you talk about?

That is where the resented question comes in. Washingtonians (by which I mean bright, aggressive, on-the-make people who come from somewhere else) assume that they are bright enough to discuss virtually anything for a good four or five minutes, but they fear that you may be more limited. If we can only find out what you know something about . . .

Thus the question -- "And what do you do?" -- is nothing more than a way of saying: and what shall we talk about? You're a lawyer? We might talk about that terribly interesting case my lawyer friend is trying. You're a doctor? We will discuss my symptoms. You work at the White House? Reaganomics will be good for a few minutes' conversation.

But suppose you sell insurance or shoes. Suppose your company makes wheel bearings. Worst of all, suppose you are a housewife. No problem. I'll simply try another gambit -- unless, as is likely, you show your resentment at not having an interesting answer to my what-do-you-do. If your resentment shows, I might suddenly pretend to spot a dear, dear friend across the room and make my way in that direction.

And there you stand, convinced of what you knew all along: that I only wanted to know if you were worth my talking to and that I have decided you weren't.