Knuckles and His Hilarious Problem is the 24th episode of the middle season.
The episode begins with K'nuckles and Flapjack digging through trash barrels on Trash Day. Flapjack calls to Captain K'nuckles to tell him he's found an entire barrel of candy that Peppermint Larry put out by mistake. After a while, eating all of that candy (having only given Flapjack two measly pieces) begins to make K'nuckles act drunk. He claims that Lolly Poopdeck's buckets are filled with tears and admits that he loves Flapjack and Bubbie. He passes out and, upon waking up, is dismayed to discover that the candy is gone. Alarmed by how K'nuckles is acting, Flapjack takes him to see Dr. Barber. Dr. Barber informs him that K'nuckles has the candy rot and proposes an appaling experimental surgery that includes putting lava rocks in K'nuckles's stomach. Horrified, Flapjack desperately suggests that he just keep K'nuckles away from candy and Dr. Barber agrees, but Flapjack is warned that if it doesn't work there's always surgery. Upon pushing K'nuckles (who's tied to a wheelchair) outside, K'nuckles tries to convince Flapjack that he had just dreamed the entire thing and that he's allowed to have candy after all. Then he tricks Flapjack into untying him so he can run away and ravage the Candy Barrel for candy. That night, Flapjack sings to K'nuckles and K'nuckles claims that Flapjack's song cured him (which is a lie). As a test, Flapjack holds a piece of candy in front of his face and K'nuckles claims he doesn't want it. But he makes a sound like a seagull, causing Flapjack to turn his head to look and then eats the candy, claiming the seagull stole it. Flapjack unties K'nuckles so they can "scramble the seagull's eggs", but K'nuckles runs away in search of candy. Flapjack finally finds K'nuckles at the Candy Trough and takes him home on the wheelchair. Seeing the horrible state K'nuckles is in, Bubbie thinks he's diseased until Flapjack tells her otherwise. Bubbie decides that K'nuckles needs some isolation time, so she ties him to a raft and sets him adrift at sea. While adrift, K'nuckles has a disturbing hallucination. He returns claiming that he's completely cured. To prove it, Flapjack and K'nuckles go to the Candy Barrel. Flapjack starts to eat a piece of candy, but K'nuckles knocks it out of his hand. Then he reveals that he still wants to find Candied Island, but to destroy it. He convinces everyone in the Candy Barrel that candy is the cause of sorrow in their lives, which leads to them dumping it into the ocean. But it turns out that K'nuckles still loves candy, which is why he tricked everyone (they actually dumped it into a rowboat he had stationed there). The episode concludes with K'nuckles tied to a wheelchair and Flapjack cheerfully saying that he's glad to have K'nuckles back.
- K'nuckles literally takes candy from a baby in this episode.
- Several other places that sell candy are seen in this episode, including the Candy Trough.
- K'nuckles' hallucination features Candy Wife "speaking".
- In this episode, Candy Wife is only seen animated (albeit, just in K'nuckles's hallucination).
- If you look closely at the scene where Dr. Barber and Peppermint Larry was licking Flapjack's arms (which have become candy canes), you can see that they're both dressed like Flapjack.
- When K'nuckles is taking candy from the barrel of candy, he is seen taking all peppermints. However, his hand was on a candy cane each time he took a piece of candy. Also note that the candy inside the barrel stayed still when K'nuckles took a piece.