"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.




Barnacle Boy and Squidward arguing.

Mermaid Man and Barnacle Boy are entering the Krusty Krab for lunch, but Squidward and Barnacle Boy have an argument. Upon realizing this, SpongeBob goes into an excited frenzy and eagerly requests 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 boatmobile 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 suddenly startled by the commotion in the kitchen which caused him to mess up one of the customers' order by accident, which results to a punch in the face. This prompts Squidward to enter the kitchen to see everything having been shrunken. Squidward at that moment discovers that SpongeBob has gained possession of Mermaid Man's belt. Assuming that SpongeBob has stolen the belt, Squidward plans to do the right thing and call Mermaid Man in order to inform him of the situation and thus get revenge. Worried that his friendship with the heroes will deteriorate, SpongeBob shrinks Squidward with the belt to foil his plan. Squidward demands SpongeBob to return him to normal size, but SpongeBob has no idea how. Due to the belt's complicated and excessive features, he instead puts Squidward through many increasingly ridiculous and excruciating feats. Squidward suggests getting Mermaid Man's help, but SpongeBob still refuses, stating someone else must be albe to help him. 

SpongeBob goes to Patrick for help, to no avail. Patrick mistakes Squidward for an action figure and starts playing with him, even after realizing that it is the real Squidward. Patrick then suggests turning 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 to and greeting SpongeBob, prompting him to shrink them so that they can't tell Mermaid Man.

A Squidward Action Figure!

Eventually, SpongeBob has shrunken everyone in Bikini Bottom and crams them all into the jar. When his mother (as one of the citizens he has shrunk) tells him he need to admit his mistakes, he then realizes he shrunk Mermaid Man and Barnacle Boy as well, and he tearfully apologizes to them. Mermaid Man accepts his apology and goes into a story about the first time he used the belt, until everyone interrupts him and demand that he tell SpongeBob how to return them to normal size. After thinking for a moment, Mermaid Man asks SpongeBob if he set the belt to Wumbo, which makes everyone realize that he does not know how to unshrink them either. The citizens form a mob and venture into SpongeBob's body, then begin assulting his internal organs and bones in a violent matter. 

This goes on a for a while until everyone realizes that SpongeBob is too big to be destructible, which gives the latter the idea to shrink Bikini Bottom before shrinking himself. The citizens are pleased with this as they see no discernable difference from their previous lives to living in a miniature Bikini Bottom. As the citizens celebrate, a bus pulls up and Plankton steps out, returning to Bikini Bottom from a vacation. He is surprised that the city is now smaller than him, and the episode ends. 




 ) 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 8 - Jeremy Wakefield [Barnacle Boy pays]
  Steel Licks 9 - 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]
  12th Street Rag 3 - Nicolas Carr, 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 1 - 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 9 - 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 - The Hawaiian Serenaders, 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 - George de Fretes, Jan Rap [ending]



  • "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. 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.[citation needed]
    • In Indonesia, this episode is usually skipped completely, either due to ads on middle of episode or possibly because it is controversial.
  • In Indonesia, instead of saying "He, she, me, wumbo," Patrick says "She is a girl."
    • Also, 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."
  • There's a book based on this episode named The Adventures of Man Sponge and Boy Patrick in What Were You Shrinking?
  • This is the first episode where 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, following "SB-129," "Big Pink Loser," "Grandma's Kisses," and "Just One Bite" respectively.
  • "My leg!": Everyone is squished inside the jar.
  • Despite SpongeBob shrinking everyone in Bikini Bottom Mr. Krabs, and Pearl did not appear in this episode.
  • This is the second episode Plankton appears bigger than the Bikini Bottomites. The first was "Sleepy Time," though it was only a dream.
  • This episode has SpongeBob's CGI cell-shaded appearance when he breaks a steel wall at the Krusty Krab.
  • After SpongeBob shrunk everyone in town Patrick is not seen again for the rest of the episode.
  • 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 Harold SquarePants.
  • This episode reveals that there is a phone in the kitchen of the Krusty Krab.
  • This episode reveals that Mermaid Man has been fighting crime for over 65 years.
  • 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 used when one is about to perform something.
  • 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.
  • Patrick explaining the meaning of the word "Wumbo" has become a popular Internet meme.
  • In the Monday Knight Slimetime marathon, this episode was paired with "I Had an Accident."
  • This episode aired on January 21, 2002, the same day as "Welcome to the Chum Bucket" and "Frankendoodle."


  • When SpongeBob is running to Patrick, one can see that the former is not wearing the utility belt in the first shot.
  • When Squidward enters the kitchen to confront SpongeBob for stealing Mermaid Man’s belt and for shrinking everything in the kitchen, the door that leads from the kitchen to Mr. Krabs’ office is gone.
    Mermaid Man and Barnacle Boy IV 040

    Mr. Krabs office door is gone.

  • 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 change 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. 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 him by accident. However, SpongeBob shrunk him on purpose, out of fear thinking that Squidward will tell Mermaid Man and Barnacle Boy about the belt situation.
  • 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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