WASHINGTON (AP) — Someone had to hold Bill Cosby back to keep him from crawling over a balcony and joining fellow comedians on stage as the stars lined up to pay tribute to his life’s work.

When the lights went out for the start of the 12th annual Mark Twain Prize for American Humor, Cosby filled the dark silence Monday night. “Hellooo?” he called out at the John F. Kennedy Center for the Performing Arts. And once again, he had his audience laughing.

Chris Rock and Jerry Seinfeld saluted their fellow funny man with the nation’s top comedy prize, along with two co-stars from “The Cosby Show,” Phylicia Rashad and Malcolm-Jamal Warner. They hailed Cosby’s work breaking down racial barriers and stereotypes and replayed his standup routines.

Cosby quipped that usually when a man sees his life flash before his eyes, it’s for a bad reason. “But this is all right,” he said.

First lady Michelle Obama and Jill Biden, Vice President Joe Biden’s wife, were among those in Washington watching clips from Cosby’s long career — from his classic standup routine of Noah’s chat with God about building an ark to dealing with the stresses of raising a family as a TV dad.

Seinfeld and Rock shared the stage and said they followed Cosby’s comedy albums as children, which inspired their own careers. Then they got lost in banter about how they could never measure up, after seeing Cosby together more recently at New York’s Apollo Theater.

“What was he wearing?” Rock said.

“Something ridiculous,” Seinfeld quipped. “But he did two hours — all new material.”

“I’m not that funny,” Rock said.

“I’m definitely not that funny,” Seinfeld said.

Instead, Seinfeld and Rock tossed to a clip of Cosby’s classic impression of a visit to the dentist.

“The first thing he grabs is an iron hook,” Cosby says in the clip. “Then he starts to drill and you see and smell smoke coming out of your mouth!”

As a clip of Cosby’s famous impression of a visit to a dentist ended, Cosby turned to his wife, Camille, who smiled and clapped. Cosby later said comedians’ wives often want autopsies of their husbands’ brains to see what’s going on in there.

Comedian Dick Gregory chimed in with jokes about his long friendship with Cosby.

“When the stock market crashed last September, they was going to repossess my Rolls-Royce,” Gregory said. “I said, ‘Bill, what do I do?’”

Cosby’s response, according to Gregory: “Don’t park in front of the house!”

Critics often point out that “The Cosby Show,” which aired in the 1980s, broke new ground because it was about a successful black family with a father who’s a doctor and mother, a lawyer, raising five children.

Gregory said Cosby started breaking barriers even earlier with the “I Spy” TV series, which cast a black man and a white man as co-stars. After that, Gregory said, promoters never again referred to him as a “Negro comic.”

“A billion years from now, you will be respected for what you were able to do,” he said, looking up at Cosby who was seated in a balcony. “You painted words with your mouth, and they will always exist, and they will always last.”

Of all his accomplishments as a comedian, actor, author and television producer, Cosby said he is most proud of the “Cosby Show,” which he carefully crafted.

Rashad, who played Claire Huxtable on the series, flew from London where she is in rehearsal for “Cat on a Hot Tin Roof” to be part of the show at Cosby’s request.

On stage, she recalled the chemistry she and Cosby shared as TV parents.

“We could complete each other’s sentences,” she said.

Warner, who played Theo on the show, said he has been in touch with his TV dad ever since. Now, he said he is far enough removed to watch himself in reruns and said the show is a testament to Cosby’s genius.

“He always said in 20 years he wanted the show to still be relevant, and here we are,” Warner said.

Cosby, 72, has won other major awards, including the Presidential Medal of Freedom in 2002. Still, the Mark Twain Prize is special, he said, because Twain was the “quintessential American writer — because he held his language and his love for words in perfect American form.”

Cosby apologized to a bust of Twain during his acceptance speech for bumping him and stealing some of his words.

The tribute will air Nov. 4 nationwide on PBS. Cosby insisted the performances at the tribute be free of profanity and that the show reflect his emphasis on education.

“The show is very, very important to me,” Cosby said in an interview. “It makes me aware that as a monologist and a writer and a performer, I’ve done some wonderful work.”

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