“Is that my cow?” the creature demanded, stepping forward unsteadily. It shook its head sadly.
“It goes Baaaa!” it wept. “It is… a sheep…”
Then it fell to its knees, clenched its teeth, turned its face upwards, like a man tortured beyond his wits, beseeching the gods of fortune and the tempest, and screamed: 

“No! That! Is!! Not!!! My!!! Cow!!!!!”

The words echoed around the cavern and broke through mere rock, so great was the force behind them, melted mere mountains, screamed across the miles…
And in the somber nursery, Young Sam stopped crying and looked around, suddenly happy but puzzled, and said, to his despairing mother’s surprise: “Co!”

– the book |
Terry Pratchett, Thud!