A Chinese Biographical Dictionary/Chang Hsüan-tsu
62Chang Hsüan-tsu 張玄祖. A wit of the Han dynasty. When only eight years old, one 王先達 Wang Hsien-ta laughed at him for having lost several teeth, and said, "What are those dog-holes in your mouth for?" "They are there," replied Chang, "to let puppies like you run in and out."