Jimmy Fallon Shares How He and Jennifer Lopez Decided to Collaborate on a Children's Book (Exclusive)

The late-night host's latest children's book, 'Nana Loves Me More,' is out now

Jimmy Fallon has something up his sleeve for his next book. ET's Rachel Smith caught up with the 47-year-old late-night host in New York City on Tuesday, and he revealed that he's collaborating with Jennifer Lopez on his next children's book.

"The next idea we have... it involves JLo and it’s massive," he promised. "We always wanted to do something together and, of course, me, I’m like, 'We should do a song together.' She’s like, 'No, I can’t. I’m busy. Oh, next time.'" 

While Lopez, 52, wasn't down for a song with Fallon, the pair did connect over their children. Lopez is mom Max and Emme, 14 year-old-twins, while Fallon has two daughters, Franny, 7, and Winnie, 8.

"We both have kids. She’s a great mom," he said of Lopez. "Let’s think of something fun, a good children’s book, that we can get together and do something."

As for what fans can expect from the book, Fallon said it's "going to help teach babies Spanish," before teasing, "It’s really cute. The artist is great. I think people are going to really dig it. It’s a lot of fun."

While fans wait for Fallon and Lopez's collab, the former entertainer is out with a new children's book of his own, Nana Loves You More.

"It's good, it rhymes, it's long enough to count as a book, but it's short enough where you can read it and go to bed," Fallon said. "... I’m excited about this one. Out of all the ones that I’ve written, this one's the closest to an actual real story. This is something you read at night to your kids. I’m excited about this."

The book touches Fallon's heart, as the Tonight Show host grew up close to his grandparents.

"My grandparents on my mom’s side lived in our back yard... in a nice cottage. After school I would go over and they would babysit me. They helped raise me. They taught me how to cook, what music to listen to, [about] comedians... I got so much from my grandparents," he said. "If you’re lucky enough to have them in your life, it’s another way of learning from someone, from a different generation, to give you advice."

Fallon warned that the book is "a little bit of a weeper," as it teaches kids that, "even when Nana’s not around anymore, you’ll always have her as a part of your life, you’ll never get rid of it, you’ll never, ever forget Grandma."

While penning the book, Fallon enlisted his kids for help, though they're more focused on writing books of their own these days.

"Winnie does the art design, Franny does the dialogue," Fallon told ET. "... They are getting to the point now with these iPads and this technology that they’re writing their own books, because they have a voice to text thing."

Fallon raises his daughters with his wife, Nancy Juvonen, who he said is the "best mom." The pair will celebrate their 15th wedding anniversary later this year, and Fallon isn't short on advice for how other couples can go the distance.

"Just take care of each other whenever you can, that’s my advice to anyone... Take out the trash, do the dishes, take care of each other. You’ll have the best time, make the best memories," he said. "It’s so much fun. That’s my partner forever. I’m so lucky to have my wife, Nancy. She’s the greatest."

Another person who Fallon considers to be the greatest in Questlove, who recently took home the Best Documentary Feature Oscar for his work directing the musical documentary, Summer of Soul (...Or, When the Revolution Could Not Be Televised).

"I was crying when Quest won the Oscar, just ‘cause I know how much work he put into that. I also know his mom so well, and they kept cutting to his mom and his mom was bawling. She's so proud," Fallon said. "Quest, who I've really never seen get that emotional, was just thinking about all the stuff that his mom and dad did for him, to get him to this position... I can't even tell you how much it meant to him, that he won the award."

And while Fallon called the onstage incident between Will Smith and Chris Rock "unfortunate," he assured fans he and other did get the chance to "celebrate with Quest" after his big win.

Nana Loves You More is out now.