Interrupting cow and the wolf in sheep's clothing / Yolen, Jane

"Interrupting Cow has a mystery to solve! Do sheep growl, groan, or howl? If not, what could this strange new creature in the pasture be? One thing Interrupting Cow does know is that there's always room for more friends!"--Publisher.

Interrupting Cow introduces a lonely wolf to her friends, and they all share her famous knock-knock joke.