While at work one day, Homer concludes that exposing a donut to radiation inside the power plant’s reactor core will increase its size. But the experiment turns disastrous, and the reactor tower is engulfed in flames. Homer tells Mr. Burns it’s his first day on the job—but Smithers corrects the lie. Furious, Burns fires Homer. Now unemployed, Homer’s interest is piqued by a commercial for the Naval Reserve, featuring footage of sailors unloading a military truck filled with beer. After filling out the required paperwork, Homer bids good-bye to his family and boards a military bus bound for boot camp. Though constantly at odds with the drill instructor, Homer successfully graduates and becomes a sailor in the Naval Reserve.

Meanwhile, Milhouse shows Bart his new earring. Bart soon notices how his fellow students treat Milhouse with new respect. Unwilling to be overshadowed, Bart visits the local mall and has his own ear pierced. He shows the diamond stud to his father, who immediately disapproves. Later, Homer learns that he has been assigned to serve aboard a nuclear submarine during war game maneuvers. As Homer says good-bye to his family, he and Bart have a heated exchange over the earring. Angered, Bart shoves his earring into Homer’s pocket. Under the command of Captain Tenille, the submarine sets sail. Tenille takes a liking to Homer, and places him in command when he leaves the bridge to inspect a torpedo tube. When an enemy vessel closes in on the submarine, Homer issues orders to fire torpedoes, shooting Captain Tenille into the water.

With most systems aboard the sub inoperable, Homer inadvertently instructs crew members to pilot the vessel into Russian waters. Wrongly concluding that Homer hijacked the sub, a United States aircraft carrier begins dropping depth charges into the sea. The sub’s engine room springs a pinhole leak and begins flooding with water. Thinking quickly, Homer uses Bart’s diamond stud to plug the leak and save the ship. Later, Homer is given a dishonorable discharge—the best anyone could hope for.