Early in our short married life, Jan and I saw the nature movie "March of the Penguins." It was after this that I began calling Jan "my penguin," meaning it as high praise, because--like my Jan--penguins have strong parental instincts, and are awesomely cute and lovable.
I saw that movie when it was in theaters, and really liked it! That really is a cute and meaningful thing to call her.