The recording industry's annual big bash reached a climax last night at the Washington Hilton when Helen Reddy announced a special dedication, positioned herself at the side of the stage and began singing "You're So Good" to William Webster, director of the Federal Bureau of Investigation.

In a sudden change of pace, the Recording Industry Association of America had given its 12th annual cultural award to the FBI -- the first time it has been given to a government organization. Last year's recipient was Beverly Sills, and others have been Joan Mondale, Hubert Humphrey, Roger Stevens and Mrs. Jouett Shouse.

The award was not given for the FBI's recent documentary recordings of the Abscam label, but for its recent undercover operations against record piracy and counterfeiting, which have become a multimillion-dollar parasite on the $3.5 billion recording industry.

Show business has not shown such affection for the G-men, probably, since the crime movies of the 1930s, and the feeling seemed almost unanimous -- though one industry veteran quipped" "When I heard they were going to give the award to the FBI, I suggested they should bring Pete Seeger down to present it."

While show business was paying its respects to the FBI, the FBI paid its respects to show business. Accepting the award, Webster displayed unexpected talent as a standup comedian. "We are a little in awe at receiving a cultural award," he said, "but we shouldn't be. We pioneered art deco and the gray fedora and the wingtipped shoe. Until recently our new building has been the architectural wonder of Pennsylvania Avenue, until I.M. Pei came along and stole our thunder."

Asked whether he was surprised at receiving the award, one of the many FBI agents in the audience (along with about 150 members of Congress and perhaps 1,000 recording executives and civilians) replied, "Not really; we've save them billions of dollars."

A break in the evening's law-abiding solemnity was provided by country singer Larry Gatlin, whose roots are in gospel music, but whose style is sometimes irreverent."We were in Tulsa a few weeks ago, and Rev. Oral Roberts came to see us," he said, "and my guitar's been in tune ever since."

A few minutes later, he introduced his controversial song, "The Midnight Choir," with the announcement, "Never in my life have I done something more innocently and gotten into more trouble. One week, it was No. 30 with a bullet; the next week, it was No. 90 with a parachute."

The song tells about a group of winos who go to the neighborhood missions to get their soup and sermon and to be saved for the third time in a week, then congregate at midnight on a street corner with a bottle of wine.

The chorus runs: "Will they have Mogen David in heaven/Dear Lord, we'd like to know/Will they have Mogen David in heaven, sweet Jesus? If they don't, who the hell wants to go?"

Galtin quoted one angry letter provoked by the song: "I'm going to pray for you children -- having such an awful daddy to write a song like that." He added:

"I wrote back: 'Go ahead and pray for me. I can use the prayers, and you can probably use the practice.'"

Then he closed his act by harmonizing a Gospel song with his brothers.

Helen Reddy also stirred up the highly political audience during a sing-along number with the threat that "anyone who doesn't sing tonight won't be re-elected."

But amid jokes about religion and Congrss, there was no levity at all about the FBI except director Webster's.

RIAA president Stanley Gortikov, announcing the award, praised the Department of Justice and the FBI for their vigorous enforcement of a 1971 law that protects the copyright of sound recording, and said that this activity "directly fosters the creative process and artistic property . . . It protects the creators from the unauthorized exploitation of their work."

"We like to concentrate on music," he said, "but it's hard."