This blonde decides she is going to prove the world that she's not a "dumb blonde". So she dyes her hair brown and goes for a drive. She comes across this beautiful pasture covered with sheep. The shepherd is standing by the fence, so she stops. She says "I bet I can tell you how many sheep you have out there."
The shepherd says "What?"
She says "Just by standing here, I can tell you how many sheep you have in that pasture."
The shepherd says "Hey, if you can do that, I'll let you have one of my sheep."
So the blonde looks out across the pasture and says "456."
The shepherd is amazed and tells the blonde to go out in the pasture and pick out a sheep. The blonde returns a few minutes later. The shepherd looks down and say "I see you found a sheep."
The blonde, looking smug, says "yup."
The shepherd says "Before you go, I would like to make one more bet with you. I bet I know what color your hair was before you dyed it."
The blonde is surprised and says "You what?"
The shepherd replies "And if I'm right, you have to give me my dog back."