A man is driving around out in the country and sees a sign in front of a house: Talking Dog For Sale. He rings the bell and the owner tells him the dog is in the backyard. He goes into the backyard to find a plain dog lying there.

“Do you talk?” he asks.
“Yes I do,” the dog replies.
“Wow!” the man says, nearly speechless, “So, what’s your story?”
The dog sits up and says, “Well, I discovered I could talk when I was pretty young. I wanted to help the government, so I told the CIA about my gift, and in no time at all they had me jetting from country to country, learning languages, and sitting in rooms with world leaders. This was before all this fancy surveillance stuff they have today. It was incredible the things I learned. I was one of their most valuable spies.”
“No kidding!” says the man.
“Yeah, but the jetting around really tired me out, and I knew I wasn’t getting any younger. I signed up for a job in Washington where I could listen in on secret meetings. I uncovered even more crazy stuff and was awarded a bunch of medals. Finally though I got me a mate, had a mess of puppies, and retired.”

The man is astonished. He goes back in the house and asks the owner what he wants for the dog.
“Ten dollars,” the owner says.
“Ten dollars?! This dog is amazing! Why are you selling him so cheap?!”
“Because he’s a liar. He never did any of that shit.”