Helen Thomas, dean of the White House press corps, says that she didn't know she was talking to a reporter when she went to dinner early in the Carter administration with Rolling Stone's Larry Sloman. And she certainly "didn't know he was writing a book."

"Ohhh god . . . Oh Lord . . . god almighty," she said yesterday when pages 389 and 390 were read to her on the phone from Sloman's new book, "Reefer Madness."

According to Sloman's account, he and friends took Thomas to dinner at the Calvert Cafe, a Middle Eastern restaurant that counts a lot of Washington VIPs among its clientele.

"The wine flowed and flowed," Sloman wrote. "Ms. Thomas got loose and began criticizing the President and First Lady. Recalling a particularly unpleasant interview with Rosalynn, Thomas noted: 'She could have marched in Hitler's Army.'"

"I didn't know he was writing a book!" Thomas said yesterday in shock. "It was a social occasion. I can't believe people who don't distinguish between working hours and social hours. I've lived a lifetime in this town separating the two."

She added: "It's a horrible remark . . . I hope it . . . The wine was flowing. It makes me mad. People say a lot of things that they don't expect to be quoted on."

She accused Sloman of "dirty pool." "I don't quote others under those circumstances and I always identify myself as a reporter."

She said, "I don't feel that way" about Mrs. Carter.

However, she said, she admits to having been disappointed at the interview, which was conducted under stiffer and more formal conditions than any other first lady had ever imposed with the veteran UPI correspondent.

Instead of receiving Thomas in the family quarters as all her predecessors had done, and giving the interviewer "a sense of how they lived," Rosalynn Carter insisted the interview be conducted in a office with a desk between her and the reporter.

At the Robert F. Kennedy Pro-Celebrity Tennis Tournament in New York on Aug. 25, publicist Barry Landau spent most of the day with the sons of Sen. Edward M. (Ted) Kennedy and former California senator John Tunney.

A few days later, Landau surfaced as one of White House chief of staff Hamilton Jordan's accusers in the Studio 54 cocaine-sniffing allegations.

Landau says that an FBI agent called him recently, wanting to talk with him about "your little friend, Teddy (Kennedy)." The FBI appears to him, Landau says, to be pursuing any possible political motivation Jordan's accusers might have because of ties to President Carter's political rivals.

The same agent who called previously, called again yesterday, Landau said, trying to set up an interview. "I've just about made up my mind to talk with them and get it over," he said.

Sen. Tunney, one of Kennedy's oldest friends, says he received a telephone warning from a lawyer in New York who told him "the FBI was investigating Landau and we should keep" Teddy Kennedy Jr. and Teddy Tunney "away from Landau."

It took a while for the warning to catch up with both 18-year-olds, who were up in Maine on a raft trip with Teddy Kennedy's aunt, Ethel.

Teddy Kennedy accepted an invitation from Landau to attend a concert given by Liza Minnelli's half-sister, Lorna Luft, at Provincetown, Mass. He came, Landau says, with his 12-year-old brother Patrick and a "governess type."

The Kennedy sons went to dinner afterward with Landau and Luft and other friends of hers, he says.

Young Kennedy was also invited by Landau to bring friends to a Liza Minnelli opening on Sept. 4 in New York, and stay overnight at Landau's apartment.

Kennedy never showed up at the second event, a spokesman for Sen. Kennedy's office says, although some of Landau's friends -- including fashion designer Halston -- have reportedly told the FBI they were under the impression that Kennedy was there.

John Tunney said yesterday that so far as he knows, the FBI has made no attempt to interview either of the two Teddys.

The boys know nothing about Landau, Tunny says, except that he was ingratiating and helpful and once worked as a volunteer in Tunney's senate office.

"I haven't seen him in years," Tunney said. "But he did call me, oddly enough, at 4:30 in the morning after this business on Studio 54 broke. I assume he wanted to talk with someone -- just anyone -- with a knowledge of politics. But I never even called him back. I was on my island in Maine and there isn't a phone, just an answering service on shore."