The Andy Griffith Show - Season 6 Episode 12
A Man's Best Friend

Opie makes friends with Tommy, the new kid in town. Tommy is a bit mischevious, climbing up on the roof of Andys building, and taking out a gun from Andys gun rack even after Andy warns him TWICE not to. Goober gets a dog which he names ""Spot"" (because there are no spots). Tommy hides one of his walkie-talkies in Spots collar and he and Opie lead Goober on to thinking that Spot can talk. The tables are turned, however, when Andy uses Tommys love of horses to teach him a lesson.