This guy 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 back
yard. The guy goes into the back yard and sees a mutt sitting
there.

"You talk?" he asks.

"Yep," the mutt replies.

"So, what's your story?"

The mutt looks up and says, "Well, I discovered this gift pretty
young and I wanted to help the government, so I told the CIA
about my gift, and in no time they had me jetting from country to
country, sitting in rooms with spies and world leaders, cause no
one figured a dog would be eavesdropping.

I was one of their most valuable spies eight years running. The
jetting around really tired me out, and I knew I wasn't getting
any younger and I wanted to settle down. So I signed up for a job
at the airport to do some undercover security work, mostly
wandering near suspicious characters and listening in. I
uncovered some incredible dealings there and was awarded a batch
of medals. Had a wife, a mess of puppies, and now I'm just
retired."

The guy is amazed. He goes back in and asks the owner what he
wants for the dog.

The owner says "Ten dollars."

The guy says he'll buy him but asks the owner, "This dog is
amazing. Why on earth are you selling him?"

The owner replies, "He's a pathalogical liar"