Peeing-eye dog
A blind man is standing at the corner with his seeing eye dog waiting to cross the street, when his pooch lifts his leg and pisses down the side of his nice, herringbone tweed trousers. The guy immediately pulls a doggie biscuit out of his pocket and offers it to the dog.
A businessman watches this from across the street. "Excuse me, sir," he calls to the blind man, "are you aware that your dog has just pissed all down the leg of your pants?"
"Yes," replies the blind man. "A dreadful habit, which I'm trying to break him of."
"Well, it's none of my business," says the onlooker, "but you're not going to teach him much by rewarding him with a biscuit!"
The blind fellow chuckles, and says, "I'm not rewarding him. I'm just trying to find his head so I can kick his butt!"