Upon learning that his son Johnny has been jailed again for drunk driving, wealthy Chicago industrialist Nils Norton arranges for him to be sent to Tucson to run a gas station. After his father advises him that if he ever meets a good woman to stick to her, Johnny boards a train on which he meets his friend Ermine, who is on her way to the University of Arizona. They drink and neck as she confesses her love for him. In Tucson, across from the gas station, Johnny finds a waffle shop run by a naïve girl from Georgia named Waffles. Johnny tells her to call him "Sugar" and, to her delight, calls her his sweetheart. The next morning, Waffles is disappointed when Johnny breaks a breakfast date to drive with Ermine and her friends to the desert. Later, Johnny returns drunk and fights Waffles' friend Tex. Upset, Waffles tells Johnny that she is going with Tex to a cabin, and this greatly disturbs Johnny. The cabin, located on Tex's property, actually houses Waffles' sick mother, who, Waffles learns, will not live much longer. When Ermine is interrogated by the university dean about her drunken trip to the desert, she says that she got the liquor from Waffles. As the dean approaches the shop to investigate, a fight breaks out inside. Blaming Waffles for contributing to the delinquency of the students, the dean instructs the student council to have the students boycott the shop or have their social privileges taken away. Reconciled, Johnny and Waffles confess their love for each other, but when Waffles refuses to promise never to go to the cabin with another man, he leaves in disgust. Although the dean forbids joyriding to the Mexican border town of Nogales, Johnny accompanies Ermine there and promises to marry her during a drinking binge. Johnny then flirts with a cafe singer on his lap, which provokes Ermine to fight the singer. Soon all the cafe's patrons participate in the melee, and many are arrested, including Johnny and Ermine. Johnny's father visits the station and, attracted to Waffles, kisses her, whereupon she slaps him. After learning that his son is in jail, Norton bails him and his friends out. At the campus dance, Waffles, to make ten dollars to buy her mother orange blossom perfume, does a quaint Southern dance and humiliates herself before the students. Upon seeing Johnny with Ermine and hearing from his father of Johnny's past phony protestations of love, Waffles runs away to the cabin. While she is there, her mother dies. The next morning, Johnny tells his father that he realizes Waffles' worth and really loves her. To protect his son, Norton offers to give Waffles anything if she will accompany him to Chicago. Not understanding his supposed lascivious intent, Waffles asks for one thousand dollars, which she needs to bury her mother in Georgia, but Savannah, her mother's black maid, chases Norton with a mop. After Savannah explains the situation, Waffles and Johnny confess their love and go with his father to Georgia.