英语故事：The Wolf and the Ostrich

A WOLF, who in devouring a man had choked himself with a bunch of
keys, asked an ostrich to put her head down his throat and pull
them out, which she did.

  "I suppose," said the Wolf, "you expect payment for that service."

  "A kind act," replied the Ostrich, "is its own reward; I have eaten
the keys."