The book I’m trying to find was probably published in the 1970s. It was mostly text, with some black and white line drawings. The storyline involved some kids visiting a fantasy world with an owl for a mayor. For the owl’s birthday, they bake him a cake in the shape of an owl. The owl is horrified and refuses to eat the cake because it looks like him. That’s all I remember, except that it also contained the word “turd” which greatly horrified my mother. It’s possible the book was written in verse, or that this was just one story in a collection, but I don’t remember. I think I had this book when I was about 10, so it was probably written for the tween market. The tone of the book was playful and irreverent.