That's an old one.


A blonde decides to start a new life of good deeds, free from people calling her stupid because of her hair. She dyes her hair brown and starts driving along a country road. She sees a farmer about to cross the road with a flock of sheep, and decides that stopping for him should be her first good deed. As he's going across the road, she leans out the window and yells "Hey, if I can guess how many sheep you have, can I have one?" The farmer has several thousand sheep, so he says "Ok." She guesses the exact number, and the farmer is amazed. "Well, what sheep do you want?" he asks. She says "How about that frisky one near the back?" The farmer gets it and gives it to her, and as she's about to drive off, he says "If I can guess your natural hair color, can I have my dog back?