Ha ha.

A postmen walks up to an isolated cottage in the country.  An old man is sitting on the porch and a rather vicious looking dog is lying down next to him.  The postman is a bit apprehensive, and says to the old man "Does your dog bite?".  "Nope" replies the old man, so the postman goes ahead and the dog leaps up and attacks him and savages his leg.  "I though you said your dog didn't bite" screams the postman.  "That ain't my dog" replies the old man.