Shari Theismann has posed for another magazine cover, this one a bit more sexy than the one she did for The Washingtonian, where she was photographed tearing up a previous cover photograph of her ex Joe Theismann. On the upcoming Dossier cover, Shari poses in a hot-pink bathing suit looking sassy, bent forward and peering out through dark glasses.

It isn't the best photograph the magazine could have chosen. Inside are better shots of the slight blond, who attributes her shapely form to exercise three days a week. The photos, though sexy in a wholesome way, will undoubtedly be seen as: Take that, Cathy Lee Crosby, here's a body worth showing off. And that's clearly the impression the magazine is trying to give in the limited text with the photographs: "Isn't it time Shari Theismann had a little fun?" and "Shari's 1986 game plan calls for making waves . . . she never has any time to think about you know who."

Shari said yesterday that she was flattered to be asked to pose and did it for fun. As for Joe and Cathy? "Who cares about them? I did it for me," she said. "I wasn't thinking about him. I don't think he cares or she'll care that I posed. Why should they? I don't care what they do. Besides, my children thought it was great. I am going to start doing more public relations work with Linda Roth and this cover will promote my name, not his."

Joe should be accustomed to this kind of thing, His current lady love, Cathy Lee, has posed for much more revealing photographs and was the subject of an entire issue of the magazine One Woman, where photographs of her ranged from demure to somewhat less than demure. Neither Joe nor Cathy was available for comment -- their unlisted phone number in Virginia is closely guarded and they can be reached only through their agents or by calling Joe's restaurant. Tipping His Hand

Either House Speaker Tip O'Neill knew more than he would admit or all those years in politics made him wise. The speaker is a man who doesn't worry much about appearing on the electronic media, especially those Sunday interview television shows that interfere with his personal time. He hadn't been on NBC's "Meet the Press" since 1977, but finally agreed to appear in a session taped in his office Wednesday.

O'Neill was asked the obvious question about the Democratic Party's presidential possibilities in 1988. He mentioned Sen. Gary Hart, Gov. Mario Cuomo and Rep. Richard Gephardt, but not Sen. Edward Kennedy. He had to be asked why he was excluding the man who was at the top of most lists. O'Neill said if Kennedy came to discuss running, he'd be glad to give advice. If Kennedy decided to run, as a friend and neighbor O'Neill would support him. The next day, the Massachusetts senator took himself out of the running.

O'Neill did not seem surprised and wasn't impressed when NBC executives were concerned about what Kennedy's announcement did to their show. He wasn't about to retape the interview that had been highly advertised. Eventually he was persuaded to sit still for a five-minute interview Friday in Boston to fix the Kennedy segment. One of his top aides said he didn't think O'Neill had discussed the issue with Kennedy. It was more likely, he added, the speaker's legendary political instincts at work. End Note

Claus von Bulow, who was acquitted in June of twice trying to kill his heiress wife, says he plans to move permanently to Europe next year. The man who since the trial posed in black leather for Vanity Fair magazine says, "I want to be forgotten and live peacefully." But then some of the wealthy Newport and upscale New York crowd may miss him. And he did make good newspaper copy . . .