Leafing through the mail, Hank notices that Bobby's birthday invitation to his Grandpa Cotton was returned. He then realizes that Bobby wrote "Hell, USA" as the mailing address. Bobby explains that Peggy told him Cotton was the devil. Bobby then recites a list of things he dislikes about his grandfather: his big plastic teeth, his incessant screaming, and his lack of shins. Hank explains that Cotton lost his shins "defending Texas in World War II." Bobby telephones his grandfather and invites him to the celebration. The day of the party, a Cadillac pulls into the driveway, a horse trailer in tow. The trailer's ramp is kicked open from the inside, and Cotton rides the horse into the Hill's backyard. Eyes shining, and assuming the animal is a gift, Bobby tells his grandfather how much he loves the horse. But Cotton explains the horse is being rented for only a few hours. Later, he gives Bobby his real present: a 20-gauge shotgun. Outraged, Peggy snatches the weapon from his hands. When Bobby is unable to break open his birthday pinata, Cotton blows it apart with the gun. Peggy thinks that Cotton ruined Bobby's party, but Bobby tells her that Cotton made it fun, much of Peggy's dismay. Peggy asks Cotton to leave the house after he smashes her good dishes. But when Cotton attempts to start his car, the engine fails to turn on. Luanne diagnoses the problem as a solenoid plunger. Peggy tells Hank she wants the "short tempered foul-mouthed old man" out of her house. But Hank tells his father he is welcome to stay.
Cotton takes Bobby to a local bar, where he harasses waitresses with sexist remarks. Meanwhile, Peggy finds the missing solenoid plunger hidden in a pair of Cotton's pants. She tells Hank that his father deliberately removed the part so he could stay at the house. Events turn even uglier when Cotton's sexist remarks begin influencing Bobby's behavior. Bobby tells his mother to get his dinner and punctuates his point by slapping her on the rear-end.
Hank admonishes Bobby for hitting his mother. He then attempts to tell his father why his behavior around Bobby is inappropriate. But before Hank has a chance to speak, his father reiterates the tale of how he lost his shins in World War II. After listening in awe to the patriotic story, Hank decides to drop the idea entirely. But Bobby is sent home from school for starting a "sexist riot." Later, Cotton takes Bobby to the Hotel Arlen and tries to buy him a prostitute (as he tried to do for Hank and his friends when they were teenagers). What Cotton fails to realize is that times have changed. The Hotel Arlen is no longer a brothel but a legitimate hotel and is hosting a convention of female trial lawyers. Hank decides his father has gone too far. He tells Cotton he won't let his son grow up to be a "woman-hating old fool" and orders him out of the house. Hank later tells Bobby that women weren't put on the earth to serve men, except he then takes him to a drive-in restaurant with waitresses on roller skates.
- Hank Hill
- Peggy Hill
- Bobby Hill
- Luanne Platter
- Dale Gribble
- Joseph Gribble
- Jeff Boomhauer
- Bill Dauterive
- Kahn Souphanousinphone
- Minh Souphanousinphone
- Connie Souphanousinphone
- Buck Strickland (debut)
- Cotton Hill
- Didi Hill (debut)
- Clark Peters (debut)
- Stuart Dooley
- During Cotton's war story, he mentions his friends Fatty, Stinky, and Brooklyn saying that they were "kinda like you fellas only one of 'em was from Brooklyn". Later in the series it is revealed that Hank was actually born in Yankee Stadium which is in the Bronx only a few miles outside of Brooklyn.
- Cotton is shown to be very astute by recognizing Kahn's ethnicity as Laotian, whereas everyone else assumes Kahn is Japanese or Chinese.
- Bobby appears to hate Cotton in the beginning of this episode as opposed to the rest of the series where he loves and adores him. Additionally, the opposite applies to Hank who appears to love and adore Cotton in this episode as opposed to being annoyed and uncomfortable with him in the rest of the series.
- As in the Pilot, Luanne is shown to be a gifted mechanic. However, in the rest of the series, she's portrayed as a dumb blonde with no mechanical aptitude.
- The title of the episode is a reference to Sins of the Fathers.