Dr Xargle's Book Of Earth Hounds by Jeanne Willis
"Good morning, class. Today we are going to learn about Earth Hounds. Earth Hounds have fangs at the front and a waggler at the back. To find out which is which, hold a sausage at both ends." Dr Xargle is instructing his class of small fellow aliens on the nature and habits of the earth creatures known to us as dogs.