N Is For Navy is the 38a episode of the middle season.
Flapjack is bored, so he asks K'nuckles for a new story. K'nuckles agrees, but only if he can use the bathroom first. After K'nuckles uses the bathroom, he tells Flapjack a story about how he fought a devil fish that ate his wife. After the story, Flapjack is amazed and asks K'nuckles how he keeps track of all his stories. K'nuckles explains that he has a life, while Flapjack doesn't. Distraught about not having a life, Flapjack goes to the bathroom and finding the adventure comics where K'nuckles gets all of "his" stories from. In the comic book, he finds an advertisement for joining the navy and decides to join so he can have a life. Upon joining the navy, Flapjack is paired up with a man who peels potatoes. Flapjack is downhearted, realizing that the navy is not really an adventure. Meanwhile, K'nuckles is horrified to discover that Flapjack has joined the navy, since the stories about the navy are exagerrated. Elsewhere, Flapjack and the other crewmates are shining the captains' boots. He angrily exclaims that shining boots isn't an adventure. In response, the captain decides that they should have a real adventure. But, to Flapjack's complete dismay, the "real adventure" turns out to be simply a marching drill. Flapjack attempts to jump overboard, but the water is swimming with sharks. He then attempts to jump into the lifeboat, but the lifeboat is also filled with sharks. In another attempt to get out of the navy, he puts potato peelings all over his face and pretends to have the scurvy, but the captain still won't let him go. Elsewhere, K'nuckles attempts to rescue Flapjack by enlisting in the navy himself. Unfortunately, Flapjack escapes just as K'nuckles is accepted, so now Flapjack has to rescue his captain. In the end, Flapjack saves K'nuckles's life after he falls off the ship.
The captain's name in one of K'nuckles' comic books is Captain Jesus