Much to the dismay of Mugs McGinnis, everyone in his East Side Kids gang (as well as the rival The Cherry Street Gang) gets to smack his rear end eighteen times in celebration of his eighteenth birthday. His mother Molly then becomes distraught when she gets a letter from his "uncle" Pete Monahan, a rancher friend of his late father, stating that he will soon visit them in New York. Molly explains to her only child that ever since his father lied to Pete that he had seven children, Pete has been sending birthday checks for each child. Pete is unaware that the McGinnises are so poor that they could never afford to return the checks.