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"Mermaid Man and Barnacle Boy IV" is a SpongeBob SquarePants episode from season three. In this episode, SpongeBob plays with Mermaid Man's secret utility belt.



Mermaid Man and Barnacle Boy are entering the Krusty Krab, most likely for lunch, and upon realizing this, SpongeBob goes into an excited frenzy, bursting through a steel wall in order to get their autograph. The heroes run away from him, accidentally leaving Mermaid Man's utility belt inside. SpongeBob finds it, and tries to give it back, but they drive away in the Invisible Boat Mobile before he can do so. SpongeBob decides to wear the belt and play with it, thinking that he could hold on to it until after work. He discovers the "Small Ray," and starts shrinking the items in the kitchen. At the register, Squidward is about to hand a muscular customer his milkshake, when the commotion in the kitchen startles him, causing him to drop the shake on the guy's head, and the guy angrily punches him in the face before storming off. Squidward enters the kitchen to see SpongeBob serving tiny Krabby Patties to cockroaches and asks SpongeBob why is everything in the kitchen so tiny. Squidward discovers that SpongeBob has Mermaid Man's belt. Assuming that SpongeBob has stolen the belt, he plans to do the right thing and call Mermaid Man in order to get revenge, and tell on him. SpongeBob fears that if Squidward tells on him, Mermaid Man will be furious and kick him out of his fan club. In desperation, SpongeBob shrinks Squidward in order to stop him. Squidward demands SpongeBob to return him to normal size, but SpongeBob does not know how to do it, as he sees that the belt includes countless other buttons, as well as complicated switches and dials, with no idea what any of them do. SpongeBob tries to use the different buttons to make Squidward big, but none of them work. Not wanting Mermaid Man to find out due to how he might react, he leaves to find someone who can help him. 

SpongeBob goes to Patrick for help, and Patrick mistakes Squidward for a "Squidward Action Figure" and starts playing with him, even after realizing that it is the real Squidward. Patrick then suggests to turn the "M" upside down, setting the belt to W for "Wumbo," which results Patrick coining the term. SpongeBob questions the validity of this, but after Patrick responds by stating the many uses of "Wumbo," SpongeBob is convinced by this idea and decides to test it out, but then he accidentally shrinks Patrick. Seconds later, citizens start coming and greeting to SpongeBob, making him shrink them so that they can't tell Mermaid Man. Eventually, SpongeBob has shrunken everyone (including his mother) in Bikini Bottom, and stuffs them into a jar. He then realizes that he has shrunken Mermaid Man and Barnacle Boy as well, and he apologizes and Mermaid Man goes into a long story to show he understands until the citizens of Bikini Bottom shout "JUST TELL HIM HOW TO UNSHRINK US!" in order to return to normal size. Mermaid Man asks him if he has tried setting it to Wumbo, which is enough to make everyone realize that he doesn't know how to unshrink them either. The people then form a mob and get out of the jar as they shout out "GET SPONGEBOB!" They go inside of SpongeBob's body and beat him (or rather, his organs) up. This continues for a while until eventually everyone says that everything is too big. This gives SpongeBob the idea to shrink Bikini Bottom itself, which satisfies the people, who see no discernible difference from their previous lives in living in a miniature Bikini Bottom. Finally, SpongeBob shrinks himself, and the tiny city begins celebrating. The closing scene shows Plankton getting off a bus, returning to Bikini Bottom from a vacation. He is surprised to see that he is now taller than Bikini Bottom.



 ) Associated production music
 ) Original music
 ) SpongeBob music

  The Lineman - Sam Spence [title card]
  Hawaiian Link (b) - Richard Myhill [opening]
  Caped Crusader - David Farnon [Mermaid Man and Barnacle Boy enter the Krusty Krab]
  Tympup (a) - Sammy Burdson, John Charles Fiddy ["Will this cover it?"]
  Steel Licks (a) - Jeremy Wakefield [Barnacle Boy pays]
  Steel Licks - Jeremy Wakefield ["I'm shaking."]
  On Fire - Gregor F. Narholz ["Must get autograph!"]
  The Lineman - Sam Spence [Mermaid Man and Barnacle Boy run from autograph hound SpongeBob, Mermaid Man forgot his belt]
  Friendly Aliens (b) - Ron Goodwin ["The emblem of submersible justice."]
  Comic Walk - Sidney Torch ["I could just hold onto it until after work."]
  The Tip Top Polka/The Cliff Polka - Chelmsford Folk Band ["Here's your shake, sir."]
  Tomfoolery - David Snell [SpongeBob shrunk everything]
  Dramatic Climax - Mike Sunderland [Squidward demands to be returned to normal size]
  Twelfth Street Rag - Sage Guyton, Jeremy Wakefield [SpongeBob zapping Squidward]
  Lovely Scenery (c) - Mladen Franko ["No! I can't let you do that!"]
  Springtime for Lovers - Len Stevens ["He'll find love one day."]
  Steel Licks (d) - Jeremy Wakefield [W for Wumbo]
  Dramatic Impact 3 - Ivor Slaney [Patrick's shrunk]
  Tympup (a) - Sammy Burdson, John Charles Fiddy [Patrick's shrunk]
  Dramatic Impact 2 - Ivor Slaney ["No! He can never find out!"]
  Steel Licks - Jeremy Wakefield [Patrick, Squidward in a jar]
  Where Danger Lurks - Ronald Hanmer [SpongeBob shrinking everyone]
  Lonely on the Beach - Jan Rap ["SpongeBob, you need to admit your mistake."]
  The Lineman - Sam Spence ["GET SPONGEBOB!", Everyone attacks SpongeBob]
  Harp Ding - Nicolas Carr ["I've got it!"]
  Sunny Samoa - Jan Rap [ending]



  • As of August 11, 2015, The Internet Movie Database (IMDB) gives this episode a rating of 8.6/10 based on 170 ratings by users.[1] users give this episode a 8.7/10 based on 153 votes.[2]
  • "Mermaid Man and Barnacle Boy IV" was ranked #90 during the Best Day Ever event on November 9–10, 2006.


  • In some airings, the scene where SpongeBob attempts to turn Squidward back to normal size by testing the various buttons on the belt is edited. The scene where Squidward is cut in half with scissors is edited out on occasion, as well as him choking and gurgling off-screen. Also, on certain airings during the scene where SpongeBob zaps people in Bikini Bottom when they say Hi to him, the flashes are cut out to possibly prevent seizures.
    • This is similar to a Pokémon episode where it made 685 viewers had seizures.
    • In Indonesia, this episode is usually completely skipped, either due to ads or possibly because it is controversial.
  • In Indonesia, instead of saying "He, she, me, wumbo," Patrick says "She is a girl."
    • As well, instead of saying "What did you? For cryin' out. What did y'all do to me?," Sandy says "What did you do until it makes you cry? What did you do to me?"
  • This is the first episode where Mermaid Man's Belt is purple with a blue M instead of a yellow M.
  • This is the first time Mermaid Man's belt is seen in purple but it's appear yellow again in "Mermaid Man and Barnacle Boy V" and it is not seen in the color purple again until "Mermaid Man & Barnacle Boy VI: The Motion Picture", which would mark the last time of his belt staying purple.
  • This is the second episode where SpongeBob is wearing a belt covering his shirt and tie through most of the episode. The first was "Hall Monitor."
  • This marks the second time Plankton appears bigger than the Bikini Bottomites. The first was in "Sleepy Time."
    • Also, in "Enemy In-Law," Plankton builds an oversized robot of him.
  • This episode has SpongeBob's CGI cell-shaded appearance when SpongeBob breaks a steel wall at the Krusty Krab.
  • The Invisible Boatmobile is revealed to a pink 1959 Cadillac in this episode.
  • This marks the only time where Margaret SquarePants is seen without Harold SquarePants.
  • This episode reveals that there is a phone in the kitchen of the Krusty Krab.
  • This episode also reveals that Mermaid Man has been fighting crime since 1937.
  • During a tribute to Ernest Borgnine, this episode was skipped for some reason.
  • When SpongeBob is reaching for the pen, he said "Keyah!" Keyah is the Tae Kwon Doe word when they're about to perform something.
  • Patrick explaining Wumbo has became a popular Internet meme.
  • All of the main characters appear in this episode except for Eugene H. Krabs.
  • This is the 25th episode appearance of Evelyn and Martin.

Cultural references

  • SpongeBob shrinking everybody in Bikini Bottom is a reference to Wayne shrinking the kids and himself including his brother Gordon, his wife Diane, and his sister, Patti from Honey, I Shrunk the Kids, and Honey, We Shrunk Ourselves.
  • One of the people who get shrunken say "What's up, Sponge?" This is a reference to Bugs Bunny's famous quote, "Eh, what's up, Doc?"


  • When SpongeBob was running to Patrick, you can see that SpongeBob is not wearing the utility belt in the first shot.
  • Even though there were a lot of cars parked outside the Krusty Krab, there were no customers inside the Krusty Krab except for Mermaid Man and Barnacle Boy.
    • When Mermaid Man and Barnacle Boy drove off from the Krusty Krab, all the cars were gone.
  • After Mermaid Man used the invisible boat alarm, and said "There she is," he was just holding his pants, but when he got to the boat, he was wearing clips on his pants, which he wasn't seen putting on.
  • The aforementioned clips holding up Mermaid Man's pants changed colors between shots.
  • Part of the invisible boat where Barnacle Boy lands painfully is a gearstick, but then he sits on the seat without moving sideways.
  • When SpongeBob gave the Krabby Patty to the cockroach, the holes on the spatula disappear.
  • When SpongeBob first shrinks Squidward and Patrick, they are comparable in size to action figures (roughly 6-8 inches). When he shrinks the rest of the townspeople, they are about the size of jellybeans. When he shrinks the whole town and then himself, Plankton is taller than the tallest building, and taller than SpongeBob was before he shrunk, despite he should in realistic proportions, be the same size as everyone else.
  • Mermaid Man is fat, but his pants does not fit him when he does not wear his belt.
  • When SpongeBob shrinks Patrick, he has the emblem on the belt set to "Wumbo," but afterwards, it is turned right side-up again.
  • When SpongeBob shrunk Sandy, Squidward and Patrick's eyes were black.
  • SpongeBob has difficulty closing the jar with everyone trying to fit in it, but when Mermaid Man mentions setting the belt to wumbo and everyone yells "What?!," it appears that they don't quite fill up the jar to the top, and he has plenty more room. This also happens when he cries "You don't understand!"
  • SpongeBob can't get the citizens of Bikini Bottom back to normal, but in "Mermaid Man and Barnacle Boy" SpongeBob mentioned a ray gun that made things grow six times their normal size. It's excusable that SpongeBob was so scared that he forgot about it.
  • In some shots of when the townspeople are beating up SpongeBob's inside, SpongeBob has bones. However, SpongeBob is an invertebrate.
  • When everyone popped out of SpongeBob, Sandy's head was missing.
  • When SpongeBob shrinks himself, Mermaid Man's belt is changed into his normal pants.


Mermaid Man and Barnacle Boy (VE)
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