Shamelessly lifted from reddit:
A molecular biologist decides to take a vacation in New Zealand. As he’s driving around admiring the scenery, he takes in a lovely vista of a shepherd on a hill with his flock of sheep. It occurs to him how quaint it would be to have a sheep grazing in his own backyard.
So, he pulls over, introduces himself to the shepherd, makes small talk for a while, and finally asks, “If I guess how many sheep are in your herd, can I have one?” There are hundreds of sheep milling about randomly, apparently impossible to count, so the shepherd says, “Sure.”
The molecular biologist glances about briefly before saying, “713.”
The shepherd, stunned, asks how the molecular biologist could possibly get that number right, and he says, “In my profession, I have to glean complex patterns from apparent chaos all the time. Child’s play.” Then he runs off to claim his prize.
But as he’s carrying it back to the car, the shepherd shouts after him, “If I guess your profession, can I have my animal back?” “Sure,” says the molecular biologist. The shepherd says, “I bet you’re a molecular biologist.”
Now it’s the molecular biologist’s turn to be stunned.
“How in the world did you know?”
“I’ll tell you in a minute. First, give me back my dog.”