After a field trip to the desert, Lisa discovers that the desert water mysteriously makes typically combative creatures get along, so she brings some of the water home as a souvenir. When Grampa moves in with the family after getting kicked out of the retirement home, Homer secretly tests the desert water on Grampa, who is instantly cured of his crankiness. A pharmaceutical representative gets word of Homer's discovery and quickly tries to replicate the water into a drug, using Grampa as the primary guinea pig. But when the pills get in the wrong hands and are sold on the black market, unexpected side effects of the new drug take an eye-popping toll on the elderly citizens of Springfield, and the Simpsons learn that their new medical cure comes with major consequences. Blackboard: 'I'm not here on a spitball scholarship'.

When Homer inadvertently humiliates Bart in front of a stadium crowd, Marge encourages Homer to enroll in a fathering enrichment class taught by therapist Dr. Zander. Shocked to learn that Homer often strangles Bart for mischievous behavior, Dr. Zander conducts a series of treatments with the help of Kareem Abdul-Jabbar to teach Homer what it feels like to be young and small. But when Bart learns that the therapy sessions have transformed Homer into a pushover, he takes advantage of Homer and becomes a school bully. Hoping therapy could also cure Bart of his bullying habits, Marge enlists Dr. Zander's help to patch their relationship. Blackboard:  'I will not ridicule teacher's final four bracket'.