"The Talking Dog.." joke

A man tried to sell his neighbour a new dog. "This is a talking dog," he
said. "And you can have him for five dollars." The neighbour said, "Who do
you think you're kidding with this talking dog stuff? There ain't no such
animal."
Suddenly the dog looked up with tears in his eyes. "Please buy me, Sir," he
pleaded. "This man is cruel. He never buys me a meal, never bathes me,
never takes me for a walk. And I used to be the richest trick dog in
America. I performed before kings. I was in the army and was decorated ten
times."
"Hey!" said the neighbour. "He can talk. Why do you want to sell him for
just five dollars?" "Because," said the seller, "I'm getting tired of all
his lies."