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 backyard.
The guy goes into the backyard and sees a black mutt just 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, because 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, "This dog is 
amazing. Why on earth are you selling him so cheap?"

The owner replies, "He's such a liar. He didn't do any of that stuff."