Terry Pratchett said this quote

“ Once again he was aware of eyes staring fixedly at him. He glanced sideways into the long, pointed face of Goodboy Bindle Featherstone, rearing up in a pose best described as The Last Puppy in the Shop.To his astonishment, he found himself reaching over and scratching it behind its ears, or at least behind the two spiky things at the sides of its head which were presumably its ears. It responded with a strange noise that sounded like a complicated blockage in a brewery. He took his hand away hurriedly.“It's all right,” said Lady Ramkin. “It's his stomachs rumbling. That means he likes you.”To his amazement, Vimes found that he was rather pleased about this. As far as he could recall, nothing in his life before had thought him worth a burp. ”