Grampa Vs. Sexual Inadequacy - Plot

Plot

When Homer and Marge's marriage becomes boring due to their fading sex life, Grampa pieces together a tonic that is guaranteed to put the sparks back into their relationship. The effectiveness of the tonic results in Homer and Grampa going into business together, selling "Simpson and Son’s Revitalizing Tonic" to the public utilizing a medicine show. They travel from town to town selling the product, but after visiting the farmhouse where Homer grew up, the two get into an argument. Grampa yells at Homer in the car, saying that if he had not taken the tonic years ago, Homer would not have been born, finally shouting "You were an accident!" Homer, deeply hurt, throws Grampa out of the car, and proceeds to shut his father out of his life. It also causes him to change the way he acts as a father to his own children, whom he vows to show the attention and love he never received from Grampa. Bart and Lisa, however, feel he is overcompensating, and find that they prefer the "old" Homer.

Bart and friends attempt to figure out why all of the adults disappear after they buy the "Simpson and Son's Tonic". They come up with numerous conspiracy theories, none of which have to do with the tonic. Lisa, a skeptic, sarcastically offers up the possibility of all the adults being "reverse vampires" and having to be home before dark, which frightens the rest of the children more than their serious ideas.

Depressed at having failed to be a good father even when he is trying, Homer goes back to the farmhouse to think. He sees old photographs, including one of himself as a child on Christmas morning, where he thinks "my dad was not even there that Christmas when I finally got to meet Santa Claus". Homer then realizes that it was his father in a Santa costume, proving that Grampa did really care for him. Homer quickly reunites with Grampa, whom by coincidence has also gone to the farmhouse to reflect. Both of them accidentally set fire to different parts of the building at the same time (Homer accidentally setting fire to the photo and Grampa throwing a bottle of his tonic into a fireplace) and bump into one another on the front porch while fleeing the blaze. The two both admit they are "screw-ups" and reconcile.