At Springfield Elementary School, Superintendent Chalmers visits Principal Skinner to show off his newly purchased 1979 Honda Accord. However, he becomes distraught when he discovers the car's hood ornament missing. Principal Skinner orders a search of every student's locker, and it is discovered that Nelson Muntz is the culprit. As punishment, Nelson is forced to return all stolen items to their owners and help Groundskeeper Willie with his jobs around the school.
Mr. Largo catches Lisa looking outside at Nelson during a music lesson, and as a result is given detention. After school, she continues to watch Nelson and develops a crush on the bully.
Lisa tries to let Nelson know how she feels about him by getting Milhouse to pass a love note to him in class. However, the plan backfires, with Nelson seriously injuring Milhouse (this is not seen, but Milhouse is seen being loaded into an ambulance), thinking the note came from him. Lisa admits that she wrote the letter and although Nelson seems indifferent about the matter he begins by visiting her house. Lisa is resolved to turn Nelson from a trouble maker into a sweet, sensitive young man. She changes his appearance by giving him new clothes and hairstyle. Later, Lisa and Nelson share their first kiss during their date at the Springfield Observatory.
However, the influence of Nelson's friends Jimbo, Dolph and Kearney proves to win out when they convince him to come along with them and throw rancid coleslaw at Principal Skinner's house. Skinner immediately phones the police, and the four flee. Nelson takes refuge with Lisa, proclaiming his innocence. Lisa believes him, until Nelson unwittingly lets the truth slip. Lisa realizes that Nelson is always going to be who he is and ends their relationship, much to the relief of an overjoyed Milhouse.
Meanwhile, Chief Wiggum arrests a scam artist for telemarketing fraud. Homer witnesses the arrest and sees the discarded autodialer in a nearby trash bin. Homer takes the autodialer home to use for tele-panhandling.
Homer ends up annoying all of Springfield with his "Happy Dude" scam, and soon enough Chief Wiggum catches him. Instead of confiscating the autodialer and taking Homer into custody, he shoots it then gives Homer a citation and asks him to bring the autodialer with him (although full of lead) to his court hearing, otherwise there would be no case and Homer would be let off the hook. In the closing credits, however, Homer has recorded a new message telling everyone he scammed he is sorry and that if they can forgive him to send more money.