LET'S TRY SOMETHING different today, okay? A little plagiarism for a change? I'll explain why as we go along. Come.

I will repeat a rumor. I cannot vouch for its accuracy. Here goes: "Secretary of State Alexander Haig reportedly has one foot on a banana peel."

That was an item in an unpublished column written by Jack Anderson, the columnist of the common man. It has since been printed many times, but with insertions and corrections supplied by the First Pencil in the land, Ronald Reagan.

To put all my cards out, I'm doing this because it is almost guaranteed to get me a call from the Oval Office and two from the seventh-floor headquarters of the secretary of state.

Jack Anderson wrote the banana peel story in a dispatch that was circulated in advance and hit the White House with hurricane force -- unlike anything that some of us ever write, I might add. David Gergen of the press office called up Anderson to deny the report. Gergen called Haig. Haig called Anderson. The president called Anderson. Haig called Anderson again, apparently just to make sure that the president had called him.

I'm sorry if this sounds like the minutes of my last condo meeting, but we in Washington feast on such illuminating detail.

You can write that Ronald Reagan is blundering into nuclear war, that his economic plan has crashed -- and nothing happens. But say that Haig's job is in danger and you immobilize the government.

The wonderful thing is that the secretary chronically threatens to resign. Even before he was confirmed, he was warning he would walk. Why, then, you ask, does he "maximize" -- to use one of his favorite words -- whenever it seems that the banana-peel option is about to be "definitized" -- to use another? Don't ask. He's never called me -- up to now, that is.

The funny thing is that Joseph Kraft -- another syndicated columnist -- first wrote the Haig-in-peril story. The roof of the West Wing did not fall in. Here is another valuable glimpse into White House mentality. Kraft's copy is chewed over in the salons of Georgetown; Anderson is the Walter Lippmann of the neighborhood saloons, and therefore more gravely regarded by the Great Communicator.

The president, having edited Anderson, is now trying to kill the whole story. Instead, with an assist from his stormy subordinate, he has given it new and pulsing life.

"I wish I could persuade you that it is unfounded," he said with wide-eyed earnestness to reporters who caught him at a "photo opportunity" -- the only opportunity, by the way, they ever get to question him.

The person Reagan really needs to persuade, however, is not us, but the secretary. Haig told Anderson that "someone in the White House has been running a guerrilla campaign against me for nine months."

The usual suspect was rounded up -- Richard Allen, White House national security assistant, a gifted sniper and Haig's natural rival. He was jocose under questioning. "Bring on the polygraphs," he chuckled.

The president doubts the existence of any such villain, and even though the bounder is behaving in a way "destructive of our foreign policy," plans no manhunt.

Alas, we cannot hope for a "smoking gun." Maybe we should look to the secretary for clues as to why the ace of spades accompanies him on his cosmic rounds.

He has never fitted in with the White House crowd. "A cobra among garter snakes" is how one anonymous observer characterized the problem. They glide around harmlessly. He comes before them, his hood swollen with pride and consequence, his voice swaying hypnotically. He makes them awfully nervous.

With a president given to one-liners, the chemistry is poor. Can you imagine Reagan's dismay when Haig, blue eyes starting, nostrils flaring, unloads something like this on him first thing in the morning.

"We want to optimize a number of anguishing inhind thaterent contradictions in the present system." That's Haig talking about the MX to the Senate Foreign Relations Committee.

Reagan doesn't mind doomsday talk. He's used to it from Caspar Weinberger, but the defense secretary is acceptably offhanded about it. The other day, asked to calculate nuclear casualties, he begged off in the sunny Reagan style: "I can't even predict the outcome of presidential elections," he said.

The real trouble is, of course, that Haig has always imagined that someone is after him, some envious dolt or other. His years in the Nixon White House fueled the fancy. For him, the "window of vulnerability" is always open. Whenever he feels a draft, he wants the White House to sneeze. The president might like a calmer spirit in Foggy Bottom, but he doesn't know anybody.

So don't think you've seen the end of the banana-peel story. Some of us are keeping it in type.

By the way, would any of you out there who were thinking of calling me up hold off for a day or two? I would like to keep the lines open for any high-level editors who might want to work over this story.