Frank is sucked down a pipe while he is in the sewer. He ends up in somebody's beer, and is drunk along with the drink. The man who drank him goes to the bathroom, and then, out comes Frank. The man gets freaked out and calls the police. Frank then performs in front of the bar during open-mike night and the police catch him and throw him in jail.
Dean is at the worst zoo of all of time, Uncle Stumpy's. Dean, being the stupidest of the Grunts, is naturally impressed by the fake animals of Uncle Stumpy's. However, the FBI shows up and arrests Stumpy and shuts down his zoo. Thinking Dean is one of Stumpy's animals, they place him in a normal zoo.
Tony is in a hospital, and they want to fix his crooked neck. The surgeons try all kinds of painful and expensive cures on Tony, but none of them seem to work. They decide they must surgically fix his neck. Tony, terrified, runs about the hospital in a doctor's disguise, resulting in him having to preform surgery on a dude.
Perry, trying to fit into human society, opens up his own repair shop. An old lady drops off her old record player to be fixed. Perry tries playing one of his favorite records, "Hooked On Grunt", on the record player. However, this attracts Satan's minions. Can Perry turn off the record before all humanity is destroyed?
Perry is the jungle and comes down with a horrible jungle disease that makes him crap a lot. The jungle natives find him and worship him like a god, trying to cure his stinky illness. In the end they are successful, but at the cost of their god being propelled from their village by the force of his own excrement.
Sammy's search for Perry leads him to a nursing home where he's mistaken for a resident. He's forced to go through the normal routines until he incites a riot by unintelligibly calling bingo numbers. He eventually ends up in the building's dungeon for causing trouble. He escapes when a fly lands on the torture wrack and stretches his limbs beyond recognition.
Tony is surrounded by people talking about corn in the city. He snaps and begins spreading a strange message of corn which somehow brings peace to all who hear it. Anyone who supports potatoes is rounded up and Tony becomes the supreme leader of a corn-based dictatorship. It all comes undone when he utters potato in front of a crowd of supporters.
Sammy somehow hatches from a chicken egg and his new chicken mom shows him the ropes around the farm. He plays with a milking machine and gets sucked into it, he's subsequently processed as cheese and left to age on a shelf. He ends up being such a ripe cheese that he's entered into the county fair. Perry turns out to be the judge, but Sammy is unable to communicate as a block of cheese and ends up being munched on by his lost brother.
Sammy and Frank find a pair of Dean Martin tickets belonging to some mobsters. The mobsters challenge them to a game of five card stud in the trunk of a car with the tickets on the line. Sammy lays out a winning hand (three Sammy cards) and they both escape by sliding down a pile of money that floods the car and into a sewer.
This picks up where season three's cliff-hanger finale leaves off. The detective recounts the events after he discovered the monastery, but he's come unhinged. Through the flashback you learn that he snooped around building but all his attempts to get in were unwittingly thwarted by the Gruntus Poobah and his servant, Ringo.
A man with an eye patch is looking for a lamp. Sammy almost nabs Perry in a bathroom by emerging from a faucet with his lamp, but narrowly misses. The man spots Sammy's lamp and challenges him to a staring duel for it. Through flashbacks its revealed that both Sammy and the man with the eye patch went through childhood training for staring contests. Sammy ultimately wins by making his left eye grow as large as his entire upper body. The man with the eye patch awakens in a doctors office where two doctors determine he needs a lucrative heart transplant.
Perry briefly appears diving into a mirage in the desert. Dean comes across a stranded Frenchman and offers him a drink from his canteen. The Frenchman becomes addicted to the drink which turns out to be Dean's sweat. He ends up turning it into an industry, bottling Dean's sweat en masse and selling it.
Gruntus Poobah flashes back to Perry's childhood. A baby boy was left on the monastery's doorstep. Gruntus Poobah took the baby in and he was raised alongside Perry and the rest. The baby grows into a bully and is cast into the monastery's steam room. He incites a rebellion and almost overthrows the Poobah, but Ringo beats the truth out of him and drops him down a pipe.