A man walks up to a street corner and sees another man with a dog sitting next to him. The first man says, "Sir, does your dog bite?"

The second man says, "Nope, sure doesn't."

The first man reaches down to pet the dog, which promptly snaps, biting off the tip of a finger.

The first man, recoiling in pain, says, "I thought you said your dog doesn't bite!"

The second man says, "That ain't my dog."