A man goes into a pet shop to buy a parrot. The shop owner points to three identical birds and says, "The parrot to your left costs $500." The man asks, "Why does the parrot costs so much?" The owner says, "Well, it knows how to use a computer. He can diagnose system bugs."
The customer asks about the next parrot and is told, "That one costs $1000 because it can do everything the other parrot can do plus it knows how to configure and use UNIX."
Naturally, the increasingly startled man asks about the third parrot and is told, "That one costs $2000." Needless to say, this begs the question, "What can IT do?" The owner shrugs and replies, "To be honest I've never seen it do a thing, but the other two call him Boss!"