Don't Let The Pigeon Drive The Bus ! By Mo Willens.

When the driver leaves the bus temporarily, he gives the reader just one instruction: Don't let the pigeon drive the bus! But, boy, that pigeon tries every trick in the book to get in that driving seat: he whines, wheedles, fibs and flatters. Will you let him drive? Told entirely in speech bubbles, this is a brilliantly original book.