"Consultant" joke

Once upon a time there was a shepherd looking after his sheep on the edge of a deserted road. Suddenly a brand new Jeep Cherokee screeches to a halt next to him. The driver, a young man dressed in a suit and Ray-Ban glasses, gets out and asks the shepherd "If I guess how many sheep you have, will you give me one of them?"
The shepherd looks at the young man, then looks at the sheep grazing and says, "All right."
The young man parks the car, connects the notebook and the mobile, enters a NASA site, scans the ground using his GPS, opens a data base and 60 Excel tables filled with algorithms, then prints a 150-page report on his high-tech mini-printer. He then turns to the shepherd and says "You have exactly 1586 sheep here."
The shepherd answers, "That's correct, you can have your sheep. The young man takes the sheep and puts it in the back of his jeep."
The shepherd looks at him and asks "If I guess your profession, will you return my sheep to me?"
The young man answers "Yes, why not."
The shepherd says, "You are a consultant!"
"How did you know?" asks the young man.
"Very simple," answers the shepherd "First, you come here without being called.
Second, you charge me a sheep to tell me something I already knew.
Third, you do not understand anything about what I do, because you took my dog!"