Transformers

Describe your pet in detail. Its physical appearance, mannerisms and personality quirks. The shape and color of the eyes, the condition of its teeth. Its breath and scent. The way it walks. Its eating quirks. How it responds to your presence, to being denied what it wants, to the unexpected, to storms.

Now use that description for a human character.

(Don't have a pet? How about a friend's pet. A favorite animal from a movie. Or give a detailed description of a person in your life and turn him or her into an animal.)