Mermaid Man Begins

"Mermaid Man Begins" is a SpongeBob SquarePants episode from Season 8. In this episode, SpongeBob and Patrick learn about Mermaid Man and Barnacle Boy's origins.

Plot
The episode begins at SpongeBob's house during a nasty wind storm, where he and Patrick are preparing to watch the Mermaid Man and Barnacle Boy marathon on television. The marathon kicks off with an origin special, but just as it begins, SpongeBob's house loses power and a strong wind blows the house and the TV away. SpongeBob and Patrick go to Squidward's house, but the wind destroys his house too, so they decide to go to the Mermalair to ask the heroes about their origin personally.

Once they are there, Mermaid Man tells them the story. He was once a regular human being who was washed into the ocean and sucked into a whirlpool. Before he could drown, mermaids came and gave him a magical starfish that enabled him to breathe underwater. Shortly after, Mermaid Man saw Barnacle Boy scraping some barnacles off a ship's hull and thought that he was drowning. He used his newfound powers to draw barnacles into Barnacle Boy's lungs, allowing him to breathe underwater as well. They then decided to become a crime-fighting duo, though Barnacle Boy argues that this was only because he was stuck breathing underwater forever as a result of Mermaid Man's actions. The two heroes go on to talk about some of their earliest rescues, but soon begin to argue about what really happened.

Just then, the actual origin special appears on the Mermalair's giant monitor. In the special, after cooking popcorn for movie night, Mermaid Man and Barnacle Boy (called Ernie and Tim respectively) are thrust into a series of nonsensical, random events. Once they return to their apartment, the overcooked popcorn strikes the two with a jolt of cosmic energy, giving them superpowers and the urge to breathe underwater. They dive into the sea and start fighting crime.

After the show ends, SpongeBob and Patrick put popcorn into a microwave with the intention of overcooking it and giving themselves powers of their own, and Mermaid Man and Barnacle Boy try to stop them.