Royal Watch: 10 days and counting. A word to the wise for the press corps planning coverage of the royal visit: If Prince Charles has that "make-my-day" look in his eyes, watch out. At odds with the British press following the Samsonite Couple around on their visit to Australia, Charles sprayed cold water all over his Fleet Street followers. Diana laughed with enjoyment.

Standing at an ornamental fountain, Charles said, "I have the greatest possible pleasure in switching on this fountain and seeing where the water goes." It went on the press corps. Officials hastily rushed to turn it off.

The incident followed a more serious warning from Buckingham Palace that the palace was seriously considering banning some British newspapers from royal media receptions that have an off-the-record rule on conversations. The prince said he was surprised and disappointed that some publications broke that rule. He also made a special point to deny a London-based story that the Australian air force had put a double bed in the plane that brought the royal couple to Australia. Why he was so upset wasn't clear. It is, after all, a long flight and they are married. But then with royal protocol, it's easy for us in the Colonies to commit unpardonable errors. Chellis: Joan Talked First

After all the grumbling about Marcia Chellis' hot-selling book, "Living With the Kennedys: The Joan Kennedy Story," Chellis has struck back. She was reacting to a statement issued almost two weeks ago by Joan Kennedy, who said Chellis' book had betrayed the tradition of Alcoholics Anonymous, "which states that anonymity is a spiritual foundation of our traditions."

In a response issued by her publisher, Simon and Schuster, Chellis said, "Nowhere in the book is AA mentioned except by Joan in public statements to the press about her involvement, which is traditionally never mentioned at a public level . . . If Mrs. Kennedy is implying my membership in AA, she is forgetting the tradition of anonymity . . . The suggestion that it is based on confidences having to do with AA is a potential disservice to the varied people I hope will benefit from the book." The book is in its fourth printing with 110,000 copies in print. It has had a $150,000 paperback sale to Berkley Publishing Corp. Matters of the Heart

Former auto maker John Z. DeLorean is never one to miss an opportunity to tell his story. His cardiologist, Dr. Chao T. Cheng, said there is no evidence so far that he suffered a heart attack Monday, but DeLorean issued a statement yesterday blaming his ex-wife's "greed" for his chest pains. He said his hospitalization was brought on because the pain of watching his children dragged into a custody battle "was more than my heart could handle."

He accused his former wife, television hostess Cristina Ferrare Thomopoulos, and her "New York lawyer," David Dean, of using the custody of their children, Zachary, 13, and Kathryn, 17, to "attempt to beat me into submission on the money and property issues between us." Dean could not be reached for a comment. DeLorean underwent other tests yesterday and was expected to be released today. End Notes

It's tough when you are working with superstars. Cher was due to fly here yesterday to receive an Outstanding Learning Disabled Achievers award at the Lab School fundraiser tonight at the new Hecht's Metro Center store. It seems the singer had an earache and couldn't fly. A limo with a color television was sent to New York to bring her back to her suite at the Bristol Hotel, where the other honorees are staying . . .

Harry Blackstone Jr. brought his magic act to the Smithsonian's Baird Auditorium last night. In honor of the 100th anniversary of his father's birth, Blackstone Jr. donated two of "The Great Blackstone's" original illusions -- the floating light bulb, designed by Thomas Edison, and the spirit handkerchief . . .

When the Nevada Society decided to have a black-tie dinner tomorrow night for two of its powerful sons, someone noticed they were both Republicans -- Sen. Paul Laxalt and Republican National Committee Chairman Frank Fahrenkopf Jr. Senate Majority Leader Robert Dole will pay tribute to Laxalt, and that won't make it a bipartisan event. So former Democratic National Committee chairman Charles T. Manatt said he will give the Fahrenkopf tribute, but Fahrenkopf will not be given equal time to respond . . .

They were still swinging hammers and putting the finishing touches on "The Treasure Houses of Britain" exhibit at the National Gallery yesterday, and proudly pinned to the shirt of each member of the construction crews was a blue button with gold lettering: "I Built the Treasure Houses of Britain."