When it comes to birthdays, no one knows how to party like Percy! Just follow his simple rules—like #2 "Happy times call for happy measures" and #9 "Be careful what you wish for"—to make the most of your celebration. Even when the cake has been consumed and the presents put away, Percy still has a trick up his sleeve to make a birthday extra special! Through clever rhymes and bright, humorous illustrations from the creators of Thanksgiving Rules and Back-to-School Rules, Percy shows how to make the most of a birthday celebration.