Boss is the biggest

There was a guy who went into a shop to buy a parrot. There werethree parrots in the shop. One was $5,000; another one, $10,000; and the third one, $30,000. The customer asked the owner, "How come this guy is $5,000? That's so expensive for this kindof parrot." The owner said, "Because I have trained him and he can talk." So the customer asked him, "How about this guy? What can he do that makes him so expensive?" The owner said, "Well, apart from talking, he can also do some amusing actions, like dancing and so on. That's why he's so expensive." Then the customer said, "How about the third one? What canhe do that makes him so expensive?" The owner of the shopsaid, "I don’t know. Normally, I have never heard him talk, nor dance, nor whistle, nor sing, nothing at all! But the other two call him 'The Boss.'"