Title is erroneous, it seems. The sheep is hidden in Geneva font. From the article: "The 18 point version of Geneva includes all the characters you’d expect, a

Title is erroneous, it seems. The sheep is hidden in Geneva font. From the article: "The 18 point version of Geneva includes all the characters you’d expect, and then, at position $D9, it has an adorable little sheep, shown at left. Other sizes of Geneva have different little icons in that location (a rabbit, a hieroglyph, a Mac icon). If you go down to the 9 point size, the sheep comes back again but is super tiny!" There are other easter egg doodles hidden in other locations that aren't accessible through typing on the keyboard. Enjoyable read, Susan Kare's Chicago font is rightly iconic.