A fellow is walking along the street and comes up to a blind man who is standing on the corner with his seeing eye dog.  As the traffic light changes, he notices that the dog has cocked his leg and is peeing on the blind man's leg.

He walks back to the blind man and says, "Excuse me sir, but do you realize your dog is peeing on your leg?"

The blind man says, "Thank you sir," and he reaches into his pocket for a treat.

The man says, "You must be one of the greatest animal lovers on the planet.  Here you are rewarding your dog, when he has done such a foul deed!"

"Rewarding him!" replies the blind man, "I'm just trying to find his mouth so I can kick him in the ass!"