You can always tell an audience by its sweet tooth. "The opera crowd eats a lot of Junior Mints," says Monty Yolles. But "kids eat Milk Duds." Yolles ought to know: He sells candy at the Kennedy Center.

And last night Yolles was prepared for an attack of the 12-and-unders. He doubled the usual Terrace Theater candy stock and threw in some extra Milk Duds. The Imagination Celebration Gala Performance and Award Presentation brings out the kids, and the kids, proving that unpredictability is their hallmark, headed straight for the Jujyfruits.

In the lobby, Mark Silverstein, 4, shook his box of Jujyfruits like a skilled percussionist and celebrated his own imagination, saying his name was "Thundercat." It gradually became clear that the name had a cause-effect link with his red plastic sunglasses. When they were on, he was the Thundercat, cool as a movie star; when off, he was just plain old Mark, shy as a violet.

Plied with chocolate, Silverstein and about 300 other kids trekked into the Terrace Theater and took their seats for highlights of the Kennedy Center's 10th annual Imagination Celebration: "The Jungle Book" in puppet-show form, the presentation of the Frances Holleman Breathitt Award for Excellence to Muppeteer Jim Henson and selected songs from "A Good Life" -- a newly commissioned musical by Jeff Moss and Stanley Silverman. "A Good Life" opens tomorrow in the Theater Lab.

"I feel like my entire life has just flashed before my ears," Henson said after a lengthy introduction by Orval Hansen, chairman of the National Education Committee. Past honorees include Maurice Sendak, Gian Carlo Menotti and Fred Rogers.

Children squirmed and writhed, sucked thumbs, switched from one adult lap to another and otherwise expressed impatience.

The Muppeteer accepted the award with haste and brought on that old crowd pleaser, Kermit the Frog. "Hi ho!" said the chipper frog, dressed for the occasion in a little tuxedo. "I wanted to come along because I didn't get the award . . . I started in Washington, and this is home." The frog then appealed to fellow frogs in the audience to make themselves heard: "I always know there are frogs in the audience if they go rib-it rib-it! Are there any frogs out there?" The audience belted out a chorus of "Rib-it rib-it!"

And the toads! "There are toads out there, I know," said Kermit. With a little prompting from the Muppet, the toads croaked "Knee-deep knee-deep!"

After the performance the kids and their escorts stormed into the Atrium for a party. Henson left Kermit backstage ("I usually don't travel with him") and braved the fans on his own, shaking little hands ("Nice to meet you, big guy!") and posing for photographs.

The crowd devoured chocolate chocolate chip cookies and apple juice, wiggled and jumped to the beat of mountain music, took in a magic show and worried about the "goody bags."

Goody bags? To a kid, that means a plastic bag with stuffed Muppets, shiny stickers, posters and pins. But one parent made them sound more like a survival kit. Goody bags, she said, are "what you give them on their way out to get rid of them. Like at birthday parties."

Or Muppet parties.