We used to read this book to our children, and they always loved it. It was especially well received by our son, though our daughter enjoyed it too. The pictures and poetry are about all sorts of slimy things. One of my favorite pages shows a hardboiled egg flying out of a man's mouth, "People with no teeth, it is said, can't eat a slimy pickled egg."
This book is pure fun, perhaps bordering on the slightly gross (which is why boys especially will go for this one). Great to read aloud to children 5 and up, and can be read by a third grader, I would guess.