An Elephant and Piggie I Will Take a Nap! Book by Mo Willems

Gerald is careful. Piggie is not.
Piggie cannot help smiling. Gerald can.
Gerald worries so that Piggie does not have to.

Gerald and Piggie are best friends.

In I Will Take a Nap! Gerald is tired and cranky. Will Piggie be in his dreams? Or will she keep Gerald from dreaming at all?