"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, but Squidward and Barnacle Boy have an argument. 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 accidentally drop the shake on the guy's head, and the guy angrily punches him in the face before storming out. 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. 

Barnacle Boy and Squidward arguing.

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.

A Squidward Action Figure!

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!", the citizens are ready to get revenge on SpongeBob, They go inside of SpongeBob's body by crushing him from the inside and beats him (or rather his organs) up and they attempted to kill SpongeBob by punching out his stomach, brain and eyes, breaking his bones and then destroying his kidney. 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 saying "Well, it's great to be back!". 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 ["You know what's funny? My pickle started out in a jar, and now it's in one again!"/"It's like a pun or something. Heheh."]
  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 [Everyone attacks SpongeBob]
  Harp Ding - Nicolas Carr ["I've got it!"]
  Sunny Samoa - Jan Rap [ending]



  • As of September 10, 2018, The Internet Movie Database (IMDB) gives this episode a rating of 8.8/10 based on 369 ratings by users.[1] users give this episode a rating of 8.7/10 based on 158 votes.[2]
  • "Mermaid Man and Barnacle Boy IV" was ranked #90 during the Best Day Ever event on November 9–10, 2006.




  • Although this episode aired on January 21, 2002, it was made in 2001 according to the credits.
  • This episode premiered in Canada on July 5, 2002.
  • 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, most likely due to the violent nature. 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 which resulted in 685 viewers having 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 episode that Mermaid Man's belt is seen in purple. It appears yellow again in "Mermaid Man and Barnacle Boy V" and is not seen 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 throughout most of the episode. The first was "Hall Monitor."
  • This is the fifth episode of the series where the Krusty Krab is featured without Mr. Krabs, and the second of the season after "Just One Bite".
  • "My leg!": Everyone is squished inside the jar.
  • This is the second episode Plankton appears bigger than the Bikini Bottomites. The first was "Sleepy Time," though it was only a dream.
    • Also, in "Enemy In-Law," Plankton builds an oversized robot of himself.
    • He is also bigger than the Bikini Bottomites in the video game Creature from the Krusty Krab in the level "Revenge of the Giant Plankton Monster."
  • This episode has SpongeBob's CGI cell-shaded appearance when he breaks a steel wall at the Krusty Krab.
  • The Invisible Boatmobile is revealed to be a pink 1959 Cadillac in this episode.
  • This marks the only episode to date where Margaret SquarePants is seen without her husband, 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 says "Keyah!," which is the Taekwondo word when they're about to perform something.
  • Irony: Squidward could've just called Mermaid Man by using the phone near the cash register instead of the phone in the kitchen, so SpongeBob wouldn't shrink him. It could be possible Squidward wanted SpongeBob to see him call Mermaid Man so he can scare him as revenge for making the muscular fish punch him earlier.
    • Another Irony: When SpongeBob says, "But there must be someone else who can help! Someone smart and wise, with years of life experience", he goes to Patrick, who isn't even smart and wise.
  • SpongeBob can't get the citizens of Bikini Bottom back to normal, but in "Mermaid Man and Barnacle Boy," SpongeBob mentions 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, it's still with Man Ray as SpongeBob mentions that he swiped the gun away, or Mermaid Man and/or Barnacle Boy dismantled it.
  • Patrick explaining the meaning of the word "Wumbo" has became a popular Internet meme.
  • It is unknown why SpongeBob didn't notice he shrunk his mother, Mermaid Man, and Barnacle Boy. It could be possible they were shrunk with other people in which SpongeBob did not notice them.
  • This is the first episode to involve shrinking. The second is "Squidtastic Voyage." and the third is "The Incredible Shrinking Sponge."
  • This is the first episode where a character shrunken is mistaken for an action figure. The second time is "The Incredible Shrinking Sponge" where SpongeBob shrinks himself from an overheated grill, and a kid fish that debuts in that episode mistakes him for an action figure.
    • In this episode, Patrick mistakes Squidward for an action figure.
  • In the Futurama episode, Parasites Lost, the Planet Express crew gets shrunk to explore Fry's body to rid of it of parasites. Like the episode, this episode also has the characters speaking normally instead of a squeaking voice while in this episode the shrunken citizens of Bikini Bottom goes in SpongeBob's body and beats him up and his organs and they attempted to kill SpongeBob because they wanted revenge on him for not returning them back to normal and for never telling Mermaid Man about what he did.
  • Eugene H. Krabs is the only main character that doesn’t appear in this episode.
  • During the scene where everyone beats up SpongeBob on the inside Patrick was not seen, and was not seen in the ending where SpongeBob shrinks himself and the town to smaller size.
  • In the Monday Knight Slimetime marathon, he was combined with the episode I Had Accident.

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 is running to Patrick, one 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 it except for Mermaid Man and Barnacle Boy.
    • When Mermaid Man and Barnacle Boy drive off from the Krusty Krab, all the cars are gone.
  • After Mermaid Man uses the invisible boat alarm and says "There she is," he is just holding his pants, but when he gets to the boat, he is 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 Boatmobile where Barnacle Boy lands painfully is a gearstick, but then he sits on the seat without moving sideways.
  • When SpongeBob gives the Krabby Patty to the cockroach, the holes on his 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 jelly beans. 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 overweight, but his pants do 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 says to Patrick that it's not a Squidward action figure but the real Squidward, he says that he shrunk it by accident. It can't be true because SpongeBob shrunk him on purpose, out of fear thinking that Squidward will tell Mermaid Man & Barnacle Boy about the belt situation and he will be kicked out of the fan club.
  • When SpongeBob shrinks Sandy, Squidward and Patrick's eyes are 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!"
  • In some shots of when the townspeople are beating up SpongeBob's inside, SpongeBob has bones. However, SpongeBob is an invertebrate.
  • When everyone pops out of SpongeBob, Sandy's head is 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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