BILLY is like sinus trouble," a White House staffer said a few years ago. "It never goes away but it never hurts that much." "There's no Billygate in sight," added Time magazine, "but the President would be well-advised to tell his beer-swilling First Brother to shut up." Billygate--a bungled White House attempt to cover up Billy Carter's ties to Libya--has now flooded Washington, of course, and no amount of Allerest or Pabst Blue Ribbon will ease the pain.

Loud-mouthed presidential brothers are nothing new, however. One has to go back to the Eisenhower era to find a president whose siblings kept their shenanigans in the shade. And even Ike's brother Edgar, a highbrow industrialist from Tacoma, Washington, liked to get in his digs at his brother the president. "Edgar's been criticizing me since I was five," Ike once joked at a press conference.

But the Eisenhower brothers kept their political disagreements largely to themselves. And, nepotism be damned, Ike drew his youngest brother Milton, a university president (Johns Hopkins) and long-time civil servant into his inner circle. Milton gave Ike important advice on his direct telephone line to the White House, and made the 40-minute drive to Washington from his home in Baltimore several times a week. It was Milton who encouraged Ike to accept the Republican nomination in 1952, and it was Milton who said he should seek a second term in 1956. He also advised Ike's 1953 atoms-for-peace proposal, consulted on foreign economic policy and education, and served as a presidential emissary to Latin America.

No one smiled cynically when Ike introduced his kid brother as "a man of whom I've always been proud to say: 'My brother Milton'." Jack Kennedy maintained an even closer relationship with his brother Bobby, and, though the two had fiercely clashing personalities, they got on famously. Familial embarrassment was noticeably absent at Camelot, despite the rumors of swimming pool orgies and Mafia links that crept through the tight Kennedy ring of privacy.

But when Lyndon Johnson inherited the Oval Office late in 1963, he brought with him Sam Houston Johnson, a sharp-witted drunk with a predilection for the fast life. "I guess Lyndon wanted me close by so that he could keep a big-brotherly eye on all my extra-curricular activities," Sam wrote in his 1969 book, My Brother Lyndon.

"He had never approved of my fancy apartment or my having a valet at the age of 23. And since he still wore baggy, ready-made suits from Sears, Roebuck, my custom-made clothes also offended his sense of prudent frugality."

Sam behaved more like Lyndon's prize Airedale than his brother. He lived in the White House with the president and Lady Bird, before, between and after his two marriages, both of which ended in divorce. Lyndon, who used to turn out the lights in Sam's bedroom to save electricity, sincerely worried about Sam's carousing and would wait for him to come home, then chew him out for drinking too much.

The president also derided Sam's sense of hunor. Shortly after Kennedy's assassination, with the country still in mourning and life in Washington finally veering toward normal, Lyndon went out of his way to pay a call on his brother.

"Sam Houston," he said, "I wouldn't be here if it hadn't been for you."

"Lyndon," responded Sam, trying to be funny, "I had nothing to do with Oswald."

"Goddamnit, Sam!" yelled Lyndon. "What the hell kind of remark is that?" The president hung up only after giving his brother a 20-minute tongue-lashing.

F. DONALD NIXON never got close enough to his presidential brother to enjoy the sweet abuse of a tongue-lashing, although once when the Nixon brothers were younger, Dick "lit into me and gave me a dressing down I'll never forget," recalls Don. "He aired all of his gripes of the past two or three years."

But as Dick Nixon the grocery clerk became Richard Nixon the politician, the gripes became political sore points. The beefy, "affable if sometimes bumptious" Don with the trademark ski-jump nose was a businessman of questionable ethics, apparently a family affliction. In the 1950s, he cashed in on his brother's vice-presidential status by opening Nixon's, a California fast-food chain that featured "Nixonburgers." When the chain developed a few weak links, Howard Hughes selflessly donated $205,000 to the cause, a loan that Don never repaid (a loan not unlike Colonel Khadaffi's contribution to Billy Carter's coffers).

The Hughes loan made for bad press during Richard Nixon's 1960 presidential campaign, and the candidate made repeated efforts to curb brother Don's financial gamesmanship. For his part, Don tried to avoid publicity. "They call me 'Big Don,'" he once said. "I'm larger than Richard. I'm not a public figure--I'm just a fellow trying to make a living. I don't want to be in the limelight at all."

But Richard wanted to insure that Don stayed out of the headlines, especially once he became president. He arranged a job for his younger brother at the Marriott Corporation, where Don's last name worked such magic that one competitor grumbled, "I don't know if he's got 'vice president' or 'brother' on his business card."

In 1973, word leaked out that Big Brother had been wiretapping Don's phone for more than a year. The White House called it a security measure, but nobody believed that for a minute. Dick was simply protecting his blind side. At the same time, Don revealed that the president even refused to talk to him: "John Mitchell is a man that I was delegated--they designated that I should talk to him about any matter pertaining to--in other words, I never talk to my brother about anything and John Mitchell was the man I was assigned to." Nixon had stonewalled his brother.

JIMMY CARTER still talks to Billy. "I admire the way he lives his own life," the president once said of his brother, who is 13 years his junior. "I have never had any occasion to be embarrassed by Billy. Billy is a good man and I'm proud he's my brother." Jimmy was proud of Bert Lance, too. Chimed in Rosalynn: "Billy is one of the best people I've ever known."

And despite the fact that he is prejudiced, that he wouldn't want his daughters to marry a Black, a hippie, backpacker or women's libber, people seem to like Billy wherever he goes, even Libya. His income several years ago reached nearly $500,000, more than half coming from the speaking invitations ($5,000 a shot) that he gets, he acknowledges, because he is the president's brother. Even Jimmy once joked at an L.A. fund-raiser, "I was hoping that you would raise enough money to have my brother Billy come out and speak next year."

Still, the two brothers keep their distance. "Jimmy don't comment on my statements and I don't comment on his," insists Billy. "You can read everything I've ever said and you won't find a political comment anywhere. Not a serious one, anyway." Even so, what if Jimmy asks him to cool it? "That's the easiest question I'll ever answer," says Billy deliberately. "He's never going to call up and tell me to change." Never? "Jimmy's staff may bitch but...to hell with his damn staff."