"It seemed like the least I could do after they saved my son's life," Jimmy Kimmel tells PEOPLE of donating his book's proceeds to children's hospitals

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Jimmy Kimmel, host of Jimmy Kimmel Live!, knows all about making people laugh. Now he wants to inspire giggles with his first children’s book, [tempo-ecommerce src="https://www.amazon.com/Serious-Goose-Jimmy-Kimmel/dp/0525707751/" rel="sponsored" target="_blank">with all proceeds to go to children’s hospitals like the one that saved his son William “Billy” John‘s life.

“My now-5-year-old daughter [Jane], I still call her ‘Goose,’ that’s my nickname for her,” says Kimmel when explaining the idea behind the book, which released Tuesday, during an exclusive interview with PEOPLE.

“When she was little, when she was in a bad mood, I’d say, ‘Are you a serious goose or a silly goose?’ And I’d try to break her out of her bad mood by going that route,” he adds. “So she would either say, ‘I’m a serious goose’ or ‘I’m a silly goose’ and it became her nickname.”

Kimmel, 52, continues, “So I call her ‘Goose,’ and I am just tickled by the idea that there would be a serious goose if there was a silly one.”

Jimmy Kimmel and family
Credit: Jimmy Kimmel/ Instagram

The picture book — which is about a no-nonsense goose who refuses to laugh, until readers help him along — took the father of four much longer to create than he anticipated. (Kimmel shares son Billy, 2½, and daughter Jane with wife Molly McNearney. He also has two older children, Kevin and Katie, from a previous relationship.)

“I thought writing a children’s book would be a very easy thing. I look through them [and think] ‘There are, like, 13 words in the whole book. What’s hard about this?’ But I also decided to illustrate it,” says Kimmel. “What really took more time than anything was the lettering, which I did. … As I was writing the word ‘goose’ for the thousandth time in a row, I regretted that.”

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Jimmy Kimmel book
Credit: Random House

But it was worth the extra effort, as Kimmel says that his younger kids love reading the book with him.

“They love doing the whole thing. My daughter will put her feet in her mouth; she really goes for it trying to make the goose laugh,” he jokes. “Even though, if she had any common sense, you’d know that the goose is going to laugh at the end, no matter what.”

While Kimmel and McNearney, 41, are relishing life with their kids, it has been a difficult journey. Billy underwent two heart surgeries — one when he was just 3 days old, and another when he was 7 months old — after he was born with a congenital heart condition, tetralogy of Fallot with pulmonary atresia. Now Billy is “doing great,” Kimmel says.

“He’s really just a normal kid, completely obsessed with T-Rexes,” the late-night host tells PEOPLE. “And we just had him make a list for Santa. We were going through Amazon and he picked 12 different T-Rex dolls. He’s only interested in T-Rexes.”

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With Christmas only a few weeks away, Kimmel says his kids are “fully engaged in making sure their good behavior is noticed now” and “really want their presents.” Case in point: Jane’s antics.

“My daughter was at the mall on a Friday. And she just started telling her friend that she was beautiful,” Kimmel recalls. “And then she said, ‘Everyone here is so beautiful.’ Then she turned to her friend and said, ‘I’m saying that because Santa’s right there.’ Because Santa was at the mall, she wanted Santa to overhear her saying nice things.”

Kimmel and McNearney get a kick out their kids’ funny comments. (“We think they’re geniuses, like every parent,” he says.) He also enjoys reading with Jane and Billy regularly — an activity that partly inspired his new book.

“We read every night and there’s a negotiation that goes on,” he says. “That’s why one of the things that was important to me was making sure you can read the book in under five minutes. That’s really what I look for when pulling books off the shelf.”

Jimmy Kimmel
Jimmy Kimmel
| Credit: Molly McNearney

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“My daughter tried to get me to grab Grimm's Fairy Tales and I’m like, ‘No, no, no, no, no, no. We’re not going to read those,’ ” he jokes.

Kimmel thinks The Serious Goose will be a fun (and short) read for kids, but he’s also glad he can assist children’s hospitals with the proceeds.

“I wanted to do something to make a big donation to Children’s Hospital Los Angeles,” he tells PEOPLE. “And not just them, but also other children’s hospitals. This will be a hefty sum. I mean, it already is. And it seemed like the least I could do after they saved my son’s life two different times.”

The Serious Goose is on sale now at amazon.com.