Grandpa and Kate are upset when Luke sells food on credit to a failing restaurant run by a widow and her daughter, but the McCoy patriarch softens his "no credit" stance considerably when he learns that the proprietress is attractive and spunky.
Amos sneaks into an air base to complain about jet noise over the farm and accidentally touches classified material so when Luke and Kate come looking for Grandpa, they are all suspected of espionage.
The McCoys are initially honored by a visit from supposedly "pro-farmer" Congressional candidate Jim Slade, but they decide to turn the tables when they learn that he has never been a farmer and is interested mainly in self-aggrandizement.
Granpda urges Pepino to marry his new girlfriend Rosita when he notices improvements in his work ethic, but the McCoys must first help him obtain a dowry by making a favorable impression on the girl's demanding Uncle Lopez.
To join a secret club known as the "Imperial Demons", Little Luke must go into an abandoned "haunted" house at night and succeed in taking a light all the way to the top floor.
Kate is expecting some women from the Garden Club to visit, and is nervous about them asking her to join. Of course, Grampa makes the wrong impression and Kate is sure that she will not get the invite.
Grandpa is stubbornly opposed to Hassie's friendship with hot rod enthusiast Eddie Collins and must be convinced that the young man is a serious engineering student and mechanic rather than a "hooligan".
After Amos mocks George's painting, cheap junk dealer Daggett pays twenty dollars for a painting by George at the McCoy farm so Amos encourages George's painting to be his manager unaware that Daggett has actually paid for the frame.
George drives into a ditch on the McCoys' property, breaking their water pipe in the process. Grampa claims he posted a warning sign, but George claims there was no sign. A lawsuit ensues.
Kate becomes upset when she learns that Luke is teaching an attractive (and unattached) young woman how to bowl, but at Grandpa's urging she turns the tables by convincing a handsome younger man to provide her with bowling lessons of her own.
Little Luke is highly resistant to the idea of taking tall and awkward Agnes Maypole to a school party, but when Grandpa finds the girl to be kind and considerate he becomes equally determined to compel the boy to honor his commitment to go ahead with the date.
