Murphy plane trip

Murphy gets on the plane sits down next thing big guy with a Stetson sits down beside him he has a dog with him.
Says Murphy your not permitted dogs on a plane, the big guy says I work for the CIA and this is a sniffer dog he can fiend drugs, money and guns with that he tells dog to seek.
A few moments later dog comes back and touches the big guy’s knee with his right paw Murphy says what’s that mean, big guy says he has found heroin he sends dog to seek again.
Dog comes back and touches big guys knee with his left paw what’s that mean Murphy asks, big guy says he has found marijuana and sends the dog to seek again.
Dog comes back shortly sits down and Shi&s what’s that mean Murphy asks big guy says he has found a bomb.