Outside the convention hall, fun is seldom the sole quest of a political party's partygoers.

"It's just like in Washington," explained Ruth Berry, press secretary of the Democratic National Convention in Atlanta. At a political convention, the parties "are social receptions but also people go there to do business."Indeed, an army of lobbyists, congressional staffers, party pros, campaign consultants, activist celebrities, and other political junkies will go to Atlanta for the Democratic Convention with no intention of stepping inside the Omni where the delegates will attend to the nomination.

They are going for the parties.

"That's where the real business goes on," said a Georgia congressional aide. His boss is a superdelegate, but the aide has no official reason for attending the convention. But he intends to take a week of vacation and go anyway.

"You see everybody, including a lot of people you haven't seen since the last political convention," he said. "It's like a reunion of the Democratic political family."

The same thing will occur, of course, next month when the Republicans hold their national convention in New Orleans.

Suspense is scant at modern political conventions, with the nomination locked up and the platform a quickly forgotten document. A conventiongoer's most memorable and meaningful experiences can occur at the so-called social events. And these outside parties - at least the ones that are well publicized - contribute to the impression that the rest of America perceives of the convention and political party itself.

Certainly the social affairs parties surrounding the 1984 political conventions reinforced some prejudices about the Democrats and Republicans alike.

At Dallas, the image of rich, country-club Republicans was not dispelled by the little ol' backyard Texas barbecue that billionaire Bunker Hunt threw at the Circle T Ranch. Sponsored by the National Conservative Political Action Committee, the party cost almost $1 million and was the talk of the convention.

Guests were met by a mariachi band and a drink to sip while walking out to a pasture for the shindig. The early entertainment included hot air balloon rides, a rodeo, a visit to a real Indian village that Chief Blue Hail and his warriors brought from Anadaroko, Okla., and stagecoach rides. The sight of Jerry Falwell sitting atop a long-horned steer was entertaining in its own right.

The guests were a Who's Who of the right wing. Pat Boone. Jesse Helms. Charlton Heston.

There were barrels of iced-down, long-necked Lone Star beer. There were servants carrying magnums around to quickly fill every empty champagne glass. There were sides of beef turning over mesquite coals and buckboard wagons loaded with Tex-Mex food and exotic fruit. These were the appetizers.

Everybody went inside an air-conditioned circus tent for a dinner of beef tenderloin and red wine.

Afterward, Bob Hope told jokes.

The same tone was set another night at a party for black Republicans that was held at Southfork, the ranch where the TV show "Dallas" is set. There were only 75 blacks among the 2,235 voting delegates at the 1984 Republican convention but four or five times that many black Republicans gathered at the home of television's Ewing family for an almost surreal affair.

Meanwhile, anybody who held the notion that Democrats were a bunch of permissive liberals was not dissuaded a whit by some of the goings-on around the party's 1984 national convention in San Francisco.

For starters, seemingly every event was attended by a hulking transvestite who called himself Sister Boom Boom. He was the self-proclaimed leader of the Order of Perpetual Indulgence, wore a shortie summer habit made of black leather, and popped up everywhere there were TV cameras.

Of course, Sister Boom Boom was at THE PARTY thrown by Willie Brown, the Speaker of the California State Assembly. Called "Oh What a Night," the party cost $300,000 and was planned for eight months. All 5,286 Democratic delegates were invited, along with thousands of visiting journalists, celebrities and crusaders of assorted causes.

The party occurred in two giant warehouses on the waterfront. The decor consisted of downsized replicas of the city's landmarks - everything from an 80-foot Golden Gate Bridge to a miniature Chinatown.