Based on the comic strip by Carl Ed, Harold courts Lillums but has competition from a wealthy banker, whose daughter gets a show going.
Harold (Hal LeRoy) writes a column and is sent to the high school, where he speaks to the seniors. He gives Lillums (Rochelle Hudson) a $22.50 bottle of perfume; but when his car is repossessed, she drops it and gets a ride with Lilacs (Chick Chandler). At the soda fountain Lilacs sings to Lillums "How Do I Know I Love You?" Harold brings back the program soaked in perfume but neglected to observe breaking news, exasperating his editor. Harold takes Lillums to the dance, while her father Pa Lovewell (Guy Kibbee) worries about his mortgage with no bank job. Harold steps on Lillums' toes, and she objects to his kicking her dog. Others laugh at Harold's inability to dance.
Harold interviews banker H. H. Snatcher (Douglass Dumbrille) while smoking a cigar, making him dizzy. Harold studies dancing from a book by Rathburn. Harold tells Lillums about Snatcher until she is sick of it, and their canoe overturns. Snatcher gives her a ride home. Snatcher takes out Lillums. Jealous Harold tells Lillums that H. H. is a "cradle-snatcher" and that she is a non-descript gold-digger. They argue, and Lillums cries. Mimi (Patricia Ellis) is offered money by her father Snatcher not to interfere, and she meets Harold. Snatcher tells Harold to take out Mimi in his car. Mimi wants a drink, and Harold takes her to the soda fountain for a Manhattan that turns out to be a banana split. Lillums sees Mimi kiss Harold.
Mimi organizes a junior league and gets dance instructor Rathburn (Hugh Herbert) to come from New York. Rathburn gives Mimi the lead, but Snatcher tells him to make Lillums the bride. Mimi complains, and Rathburn makes both brides. Lillums worries about her parents with Harold. Snatcher sends Lillums a wedding gown with a veiled proposal. In the show Mimi sings "Two Little Flies on a Lump of Sugar" with Lilacs. Mimi sees Lillums' dress and complains to her father, making him realize that Lillums is too young for him. Lilacs and others sing "Collegiate Wedding." Instead of Mimi, Harold falls down the stairs. Lillums tells him to save the show, and he tap dances with extraordinary skill. Harold kisses Lillums. They wed, and Snatcher gives her father his banknote. Harold and Lillums drive away.
In this musical comedy teens manage to play off a predatory banker, whose mature daughter puts in perspective his intention to wed a high-schooler. Somehow the young energy in the soda fountain is refreshing, and they are less affected by financial worries than their parents.