Because you know it's going to be hilarious. And, though you've read every single other book Mo Willems has ever written, you know you won't be able to predict the direction the story will take. Plus the newest Elephant & Piggie title is actually called Waiting Is Not Easy! Piggie has a surprise for Gerald, but he is going to have to wait for it. And wait. And wait some more.... Oh, the exquisite agony!
Find all of the Elephant & Piggie books in the Kid Zone. The call number is E WIL.