Cowboy Bob and Cowboy Roger kept each of their horses in the same field. To help tell them apart, Bob tied a red ribbon to his horse's tail and Roger tied a blue ribbon to his horse's tail. The next morning, when they went to check on their horses, they noticed that the ribbons had fallen off of the horses' tails.

"Now how will we tell our horses apart?" Bob said despairingly.

Roger mused for a moment, then was struck by an idea. "I know... how about if you take the brown one and I take the grey one?"