Counting Sheep............

A blond died her hair brown because she was tired of being picked on,
She was driving along the countryside when she got a bright idea and stopped at a nearby farm. she said to the farmer "If i can tell you how many sheep you have in total can I have one?"
"OK" said the farmer, so she quickly counted them and said 91. The farmer looked around astonished and said "alright take one"
As she was walking back to her car the farmer said "If i can guess your natural hair color can i have my dog back?"