The Andy Griffith Show/Opie Loves Helen
From The TV IV
Opie develops a crush on a secret girlfriend, and gets advice on what kind of present to get her. When he comes up with a pair of nylon stockings, Andy intercedes, suggesting something less personal, like flowers. Later, Andy discovers that the secret girl is Opie's teacher, Helen Crump. Andy informs Opie that he doesn't appreciate him cutting in on his girl, and Opie relents.