Perfect for children just learning to read, this highly original book is told entirely in speech bubbles with a repetitive use of familiar phrases. From the award-winning author of the multi-million-copy-selling Don''t Let the Pigeon Drive the Bus!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 Happy Pig Day!, Piggie celebrates her favourite day of the year. But will Gerald the elephant be included in the festivities...? Mo Willems creates another hilarious escapade starring the award-winning duo that will have early readers breaking into laughter from the first page.