"The Serious Goose" is Kimmel's brainchild. It's an original story he wrote. Why a goose?
"It's goose because my daughter, Jane, who is 5-year-old now, when she was in a bad mood, I'd say, 'Are you a silly goose or a serious goose?' And she'd say, 'I'm a serious goose!' So her nickname became Goose. And that's why I chose the goose. And the goal of the book is to make the serious goose silly," Kimmel said.
Kimmel also decided he'd illustrate the book himself -- and do all the lettering by hand! When he was a kid, he wanted to be an artist.
"It was basically me at the kitchen table with a million pieces of paper and a million different pens and ink all over my hands and my wife going, 'Hey, when are you gonna be done with this already?' And I'd say, 'Take the kids out of the house. I need time," he said.
"The Serious Goose" was actually a labor of love. Kimmel is donating every penny he makes from it to Children's Hospital Los Angeles and other children's hospitals across the country. He already knows it's at least $1 million. He's been involved with the hospital from the moment his son, Billy, needed two heart surgeries.
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"They love what they do," he said, "and they need to be funded."
Over the weekend, Jimmy signed books for fans at the Barnes & Noble at The Grove in Los Angeles.
"The Serious Goose" is just one way he gives back, something his parents instilled in him long ago.
"Besides it being the right thing to do, it is one of the most satisfying things to do. And I think it's very important to show that to your kids, to let them see you doing these things and to have them be a part of it, too," Kimmel said.