I Spy is an American television secret-agent adventure series. It ran for three seasons on NBC from 1965 to 1968 and teamed Robert Culp as international tennis player Kelly Robinson with Bill Cosby as his trainer, Alexander Scott. The characters' travels as ostensible "tennis bums", Robinson playing talented tennis as an amateur with the wealthy in return for food and lodging, and Scott tagging along, provided a cover story concealing their roles as top agents for the Pentagon. Their real work usually kept them busy chasing villains, spies and beautiful women. Wikipedia
Alexander Scott: Has anyone told you how good you look in that?
Kelly Robinson: Why, no...
Alexander Scott: Well, if they do, smack 'em in the face real fast, because they're not your friend.