I Am Invited to a Party! 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 Am Invited to a Party! Piggie is invited to her first party. She doesn't know what to wear, though, so she asks her best friend Elephant for help. Elephant's advice is odd to say the least, so Piggie will try on all sorts of zany outfits before finally arriving at the party for a hilarious surprise.