One day in Bikini Bottom, SpongeBob wiped the grill with an old rag at the Krusty Krab, and he proclaims that it is freshly clean and tries to convince a customer to eat a Krabby Patty that was on the grill. When SpongeBob went back inside to cook that patty, the customer asks Squidward why he doesn't want a Krabby Patty, and he replies "I've seen what he cleans the grill with." It goes back to SpongeBob, who is on his way to the freezer for a patty when he slips on a puddle of water. Upon closer inspection, SpongeBob observes that the flood is coming from the sink, which is clogged with water. As he is trying to figure out how to unclog the drain, Patrick comes in and slips, but because he was his normal clumsy self.
Eventually, Mr. Krabs overhears them trying to pull the drain, and stops them before they have a chance. They hear the story of the Main Drain, and Mr. Krabs tells the story. The story was that there was a plug that two kids supposedly pulled long ago that ended the world of Bikini Bottom. When they ask him where it is, he becomes nervous and tells them to go away. The two go outside and SpongeBob steps on Plankton, and then they ask him about it. He becomes nervous also and tells them to go away. SpongeBob says that he heard it from Mr. Krabs, and Plankton claims Mr. Krabs was lying. They ask him where it is and again, no results. They turn to Old Man Jenkins, but he yields no results.
Then they go on the adventure for the plug by dragging Patrick's house. Just before they pull the plug, Mr. Krabs and Plankton stop them and tell the story of how they were the ones that pulled the plug when they were younger. They explain that they lied because they didn't want SpongeBob and Patrick to look for it. Unfortunately, Patrick already pulled the plug and everything (including themselves and the Bikini Bottomites) was sucked into the drain.
Patrick then sits up in his bed, after hearing SpongeBob's story of the drain, and claiming it's as the most realistic story he has ever heard, indicating everything happens on the episode was only SpongeBob's story.
( ‣ ) Associated production music
( • ) Original music
( ◦ ) SpongeBob music
• ? - Sage Guyton, Jeremy Wakefield [title card] • ? - Michael Bolger, Nicolas Carr [SpongeBob exits the freezer/SpongeBob cleaning the grill] ‣Dramatic Bridge 4 - Phillip Green [SpongeBob slipping] • ? - Nicolas Carr ["Where'd all this water come from?"] ‣Clumsy C - Bernd Gesell [sink clogged] ‣Killer Birds - Gregor F. Narholz ["Pull the drain plug."] • ? - Jeremy Wakefield ["What in Neptune's bathtub do you think you're doing?!"] ‣ ? ["Hmm... One sec."] ‣Agitation Bridge 3 - Phillip Green [Krabs' scary story] ‣Domestic Fun (a) - Ernest Tomlinson [kids wandering through the ocean] ‣Domestic Fun (b) - Ernest Tomlinson [they pull the drain plug] ‣Epic Adventure - Dick Stephen Walter [kids sucked down the drain] ‣Dramatic Encounter - Gregor F. Narholz ["And nobody was ever heard from again."] • ? - Jeremy Wakefield ["I don't know where it is!"] ‣ ? ["The main drain sounds very dangerous."] ‣Drama Link (g) - Hubert Clifford ["The main drain?"] •Comic Walk - Nicolas Carr [Plankton says there is no main drain] ‣ ? ["Why would Krabs tell those two blunderers about the main drain?"] ‣Befuddled Gent - Phillip Green ["Old Man Jenkins!"] •Steel Sting - Jeremy Wakefield ["I have no idea."] ‣Buccaneers [#91] - Harry Bluestone ["Patrick, we need to find that drain!"] ‣ ? [Patrick thinking] • ? - Jeremy Wakefield [Patrick babbling] •Gator - Steve Belfer [SpongeBob blowing bubbles] ‣Variety Link (d) - Dick Stephen Walter [bus-shaped bubble] ‣Editor's Falling Over (b) - Dick Stephen Walter [bubble pops] ‣ ? ["I know!"] • ? - Jeremy Wakefield [SpongeBob blows a bubble] • ? - Sage Guyton, Jeremy Wakefield [Patrick's house floating up] ‣Drama Link (d) - Hubert Clifford [SpongeBob and Patrick scream] • ? - Jeremy Wakefield ["Another miserable day."] ‣ ? [Patrick gets an idea] ‣The Jovial Buccaneers - John Fox [Patrick pulling his house] ‣Hide and Seek - Harry Bluestone, Emil Cadkin [they find the drain] ‣Finger of Fear - Fredric Bayco ["Why would we do that?"] ‣Dramatic Impact 3 - Ivor Slaney ["NO!"] ‣Dramatic Impact 2 - Ivor Slaney [SpongeBob and Patrick gasp] ‣Domestic Fun (a) - Ernest Tomlinson [flashback to Krabs and Plankton as kids] ‣Epic Adventure - Dick Stephen Walter [everything sucked down the drain] • ? - Jeremy Wakefield ["We had to lie to keep you from looking for it."] ‣Dramatic Impact 6 - Ivor Slaney [Patrick pulls the drain plug] ‣Epic Adventure - Dick Stephen Walter [everything sucked down the drain] • ? - Jeremy Wakefield [ending]
Though it's revealed that this episode was only a story being read to Patrick by SpongeBob, the entire population of Bikini Bottom was sucked away before: in the episode A Flea in Her Dome, everyone was sucked into Sandy's Treedome. This event could have been the inspiration for this story.
The Main Drain, which sucks in all of Bikini Bottom, obviously refers to the end-of-the-world scenario "killer strangelet."
Like his arms and legs, SpongeBob's tongue can also be detached and reattached.
This is the second time Mr. Krabs and Plankton were friends and kids. The first was Friend or Foe.
Originally this episode and some others were originally on a DVD before the episodes aired on TV. The DVD name was The Legends of Bikini Bottom.
Unless the sink drain was directly connected to the Main Drain -which is highly unlikely- pulling the sink drain would not have any major effect.
It was revealed in this episode when SpongeBob and Patrick are seen flying on Patrick's house intended with bubble made balloons. This scene of Patrick's house is similar to Mr. Fredrickson's house from a 2009 Disney/Pixar film Up.