A blind man is walking down the street with his guide dog when it leads him to smack into a post.

Once he's recovered,the blind man reaches into his pocket and fetches out a treat to feed the dog.

A passer-by remarks: "That's marvellous! Even after he's made a mistake like that, you're giving him a treat."

"Not really..." Says the blind man. "I'm just trying to find which end is which so I can kick him in the bollocks!"