Pharrell Williams is writing a children's book. You'll never guess what it's based on.

We apologize for getting "Happy" stuck in your head again. But Pharrell Williams is going to author four picture books -- and the first will be based on this hit song.The books will be published by Putnam, a division of Penguin-Random House known for the "Where's Spot?" series, reports the Associated Press. "Happy!" will be filled with photos of children from around the world "celebrating what it means to be happy," reminiscent of the 24-hour music video released with the song.