As Comicstriphero would say, I love this joke so much I want to marry it. I'm a farmer's daughter, what can I say. You can take the girl out of Curramulka, etc.
NB dated technology; a skilled cultural historian could tell you when this joke originated, not only to the year but possibly also to the month.
A farmer is attending to a mob of sheep in a remote paddock when suddenly a brand-new BMW advances out of a dust cloud towards him. The driver, a young man in a Broni suit, Gucci shoes, Ray Ban sunglasses and YSL tie leans out the window and says "If I tell you exactly how many sheep you have here, will you give me one?"
The farmer looks at the man, obviously a yuppie, then looks at his peacefully grazing mob and calmly answers, "Sure. Why not?"
The yuppie parks his car, whips out his Dell notebook computer, connects it to his AT&T cell phone, surfs to a NASA page on the internet, where he calls up a GPS satellite navigation system to get an exact fix on his location which he then feeds to another NASA satellite that scans the area in an ultra-high-resolution photo.
The young man then opens the digital photo in Adobe Photoshop and exports it to an image processing facility in Hamburg, Germany. Within seconds, he receives an email on his Palm Pilot that the image has been processed and the data stored. He then accesses a MS-SQL database through an ODBC connected Excel spreadsheet with hundreds of complex formulas. He uploads all of this data via an email on his Blackberry and, after a few minutes, receives a response. Finally, he prints out a full-color, 150-page report on his hi-tech, miniaturized HP LaserJet printer and finally turns to the farmer and says, "You have exactly 1586 sheep."
"That's right. Well, I guess you can take one of my sheep," says the farmer. He watches the yuppie select one of the animals and looks on amused as the young man stuffs it into the trunk of his car.
Then the farmer says to the young man, "Hey, if I can tell you exactly what your business is, will you give me back my sheep?"
The young man thinks about it for a second and then says, "Okay, why not?"
"You're a consultant," says the farmer.
"Wow! That's correct," says the yuppie, "but how did you guess that?"
"No guessing required," answered the farmer. "You showed up here even though nobody called you; you want to get paid for an answer I already knew to a question that I hadn't asked; and you know absolutely nothing about my business. Now give me back my dog."