Here is a comic strip by Ryan Lake that illustrates the concept of Russell's turkey. The idea is simply the induction does not always work the way you expect. There could be some factors, which did not have influence on the training data, yet changing the learned concept dramatically. We should thus keep in mind that machine learning (which is based on induction) is not the panacea.
PS. I am reading Animal Farm by George Orwell now, it is a great animal metaphor too.