"Killer Dogs" joke

A man went to the hardware store with his Great Dane and when he arrived, he tied the dog up outside and went in to shop.

A few minutes later, another fellow walked in and the following conversation ensued:

Second man: Is that your dog outside?

First man: Yes. What of it?

Second man: Well, I think my dog may have killed him.

First man, stunned: What kind of dog do you have that can kill a Great Dane?

Second man: Well, he's a Chihuahua.

First man: Ha! How can a Chihuahua kill a Great Dane?

Second man: Well, I think he may have gotten stuck in his throat.