- SpongeBob SquarePants
- Squidward Tentacles
- Patrick Star
- Eugene H. Krabs
- Gary the Snail (cameo)
- Incidental 107
- Incidental 116
- King Neptune (mentioned)
- Bikini Bottomites
Squidward is relaxing in his bathtub when SpongeBob and Patrick, who are playing with SpongeBob's old baby toys, disturb Squidward, who comes out and demands them to stop making noises and act mature. However, SpongeBob and Patrick do not listen. Squidward walks back to his house, but he slips on a toy along the way and hits his head. His injuries to the head cause him to act like an infant himself. SpongeBob and Patrick then bring him to the hospital.At the hospital, a doctor tells them that Squidward has developed a mental disorder called "Head-Go-Boom-Boom-Itis" due to his head trauma. It means he is mentally and socially an infant despite being an adult. The doctor also says that his head must be protected from more injury, or else he will likely remain infantile.
However, later at SpongeBob's pineapple, when SpongeBob decides to feed Squidward, Patrick hurts Squidward's head by tossing him up into the ceiling. SpongeBob reminds him that they are supposed to protect Squidward's head, not hurt it more. SpongeBob tries to feed Squidward, but he does not like his food and spits it all over SpongeBob. Patrick licks the food off SpongeBob's face and thanks Squidward for sharing. Then, they try to entertain Squidward with some games. They start off with "Kelpy Cake," but when Squidward does it, he ends up slapping SpongeBob and Patrick repeatedly, sending them flying into the air and out of the house into the street.
Squidward escapes, and SpongeBob and Patrick follow him as he crawls out to the street, where a truck is about to hit Squidward. The truck driver is asleep, but Patrick is able to protect Squidward and lift up the road to send the truck flying. However, when Patrick drops the road back into place, he accidentally smashes Squidward's head again. Then, SpongeBob and Patrick go back inside and put Squidward in a cage.
He cries for several days. Then, three days later, SpongeBob goes to work with Patrick and asks him if he can watch Squidward while he works, but Patrick, tired from taking care of Squidward, falls asleep on a table.
SpongeBob informs an angry Mr. Krabs that Squidward has the mind of an infant and cannot work. Mr. Krabs does not care, since there are customers outside the door, literally begging to give Mr. Krabs their money. SpongeBob then gets an idea. He brings Squidward to the cash register and puts him in a high chair. When Squidward drops his head on the cash register, SpongeBob duct-tapes him to the seat so he cannot escape. When Mr. Krabs lets the customers in, Squidward sucks on a customer's hand and head and SpongeBob stops him.
SpongeBob then gives Squidward the order papers to write orders on, but Squidward instead doodles on them and throws them into the kitchen. SpongeBob asks him if it will be for there or to "goo." SpongeBob peeks out the order window and sees Squidward doodling on Nat Peterson's face. Nat screams and ends up running out of the restaurant. Pilar scolds Squidward for not taking an order. Squidward types in something then he bangs his jaw on the cash register and wails loudly.
SpongeBob thinks Squidward is crying because Pilar yelled at him and SpongeBob tells Pilar he should be ashamed. Squidward then dirties his diaper. The customers smell the horrible stench of Squidward's diaper and Mr. Krabs tells SpongeBob to change it. Everywhere he goes to change Squidward's diaper, people are sitting or getting condiments or walking. Mr. Krabs tells SpongeBob to take Squidward to the kitchen, where the food is prepared, and change it. This disgusts the customers, so they leave.
Mr. Krabs tells SpongeBob to get Squidward out of his restaurant. SpongeBob cries and tells Mr. Krabs that if Squidward is not welcome there, he is not staying either. However, on the way out, he ends up slipping on Squidward's baby rattle and slips into the kitchen, where he bangs Squidward's head on the frying pans and the fryer.
Squidward falls into the ice machine and ice pours out onto Squidward's head, curing his head trauma and returning him to his adult state. SpongeBob is relieved that Squidward is "grown-up again" and a confused Squidward asks why he would not be grown up. He notices that he is wearing a diaper and that it is full.
When SpongeBob is about to tell Squidward that he was going to change him, a deadpanned Squidward tells SpongeBob to not say another word about that experience, ever, and then leaves the scene. SpongeBob then replies, "Kids, they grow up so fast" as the episode ends.
|( ‣ ) Associated production music|
|( • ) Original music|
|( ◦ ) SpongeBob music|
• Bathroom Nirvana - Nicolas Carr [opening]
• Toy Piano - Nicolas Carr, Barry Anthony ["How do you like that, baby?"]
• A Fishy Conversation - Barry Anthony [box of baby toys]
• Who Said That - Nicolas Carr, Barry Anthony ["I'd appreciate some quiet!"]
• Hot Steel and Slide Licks 8 - Jeremy Wakefield [SpongeBob, Patrick cry]
• Grass Skirt Chase - Sage Guyton, Jeremy Wakefield [Squidward hits his head on the mailbox]
• Tension Bits - Nicolas Carr, Sage Guyton, Jeremy Wakefield [Squidward's head swells up]
• Hot Steel and Slide Licks 5 - Jeremy Wakefield [SpongeBob, Patrick take Squidward to the hospital]
• Soapy Organ - Hiram Titus [At the hospital]
• A Casual Conversation - Nicolas Carr, Barry Anthony [Feeding Squidward]
• Clowning Around Again - Nicolas Carr, Barry Anthony [Patty cake]
• Hot Steel and Slide Licks 1 - Jeremy Wakefield ["This game's kinda dangerous."]
‣ Rescue - Cecil Milner [Squidward wanders away]
‣ Trade Fanfare [#48] - Gerhard Trede ["Hooray!"]
‣ Prologue of a Drama #9 - Hans Conzelmann, Delle Haensch [Squidward's head flattened]
• Hot Steel and Slide Licks (i) - Jeremy Wakefield [SpongeBob picks Squidward up]
• Fooling Around 2 - Nicolas Carr, Barry Anthony [Squidward in cage]
‣ The Bachelor Life (c) - Laurie Johnson [plays on TV]
• Humorous Conversation - Nicolas Carr, Barry Anthony [Squidward crying incessantly]
• Tip Toe Jig - Michael Bolger, Nicolas Carr [72 hours later...]
• Salty Squid Jig 2 - Michael Bolger, Nicolas Carr, Sage Guyton, James King ["Hop to it, boys!"]
• Hot Steel and Slide Licks (m) - Jeremy Wakefield [Squidward cries]
‣ Drama Link (b) - Hubert Clifford [dirty diaper]
• Hot Steel and Slide Licks 14 - Jeremy Wakefield [customers groaning]
• Melodramatic Moments - Michael Bolger, Nicolas Carr ["Mr. Squidward, where are your manners?"]
• Hot Steel and Slide Licks 16 - Jeremy Wakefield [Squidward's diaper is full.]
• An Underwater Conversation - Barry Anthony [changing Squidward's diaper]
• Hot Steel and Slide Licks 5 - Jeremy Wakefield [customers leaving]
• Sad Sailor Waltz - Michael Bolger, Nicolas Carr [Mr. Krabs, if my poopy baby isn’t welcome here, then I’m not staying either!"]
• Porous Pursuit - Nicolas Carr, Sage Guyton, Jeremy Wakefield [SpongeBob trips on a rattle]
‣ Drama Link (g) - Hubert Clifford ["Squidward!"]
• Vibe Q Sting - Nicolas Carr ["What the...?"]
• Coconut Cream Pie Dry - Nicolas Carr, Sage Guyton, Jeremy Wakefield [ending]
- This episode was released on iTunes on September 8, 2012 as part of SpongeBob SquarePants Vol. 15 and is also available on the SpongeBob LongPants, Evil Spatula, Complete Ninth Season, Next 100 Episodes, and The Best 200 Episodes Ever DVDs.
- This episode was paired up with "The Good Krabby Name" during the original airing, but has since been re-airing with "License to Milkshake."
- This episode and "The Good Krabby Name" premiered right before a commercial-free airing of the original version of the 1982 Universal Pictures movie E.T. the Extra-Terrestrial, in celebration of the film's 30th anniversary at the time.
- Some of the toys in the baby toy box resemble the one from the skill crane from the episode of the same name, including an octopus and a teddy bear.
- When Squidward hits his head, it expands, but it is unknown why his nose shrunk.
- Itis is a suffix for swollen or inflammatory. This is one of the few episodes to use the suffix outside of its actual meaning. In this case, Purple Doctorfish tells SpongeBob and Patrick that Squidward is suffering "Head-go-boom-boom-itis." Squidward suffered neither of those.
- When baby Squidward draws on Incidental 41's face, Incidental 41 says, "My face, My face! Also my leg, but mostly my face!," is the first time after "Shuffleboarding" where the "My leg!" gag has not been heard but is referenced.
- This episode and "Gary in Love" both end with SpongeBob saying, "They grow up so fast."
- He also says a variant at the end of "Bubble Buddy:" "They blow up so fast!"
- This is the second episode where Squidward has a change in appearance due to his injury. The first is "The Two Faces of Squidward."
- This is the second episode where Squidward becomes a baby. The first is "Goo Goo Gas."
- This is the second episode where SpongeBob and Patrick act as parents. The first is "Rock-a-Bye Bivalve" with Junior.
- The scene where Patrick watches TV while SpongeBob carries Baby Squidward is a reference to "Rock-a-Bye Bivalve," where Patrick slacks off while SpongeBob takes care of Junior.
- This is the second episode where Patrick lifts up a road. The first is "What Ever Happened to SpongeBob?"
- In the Arabic dub, this episode is called "إصابة الرضع," which translates to "Infection of infants."
- In the French dub, SpongeBob says both "Squidward!" and "Carlo !" at the same time right after Squidward crashes his head into his mailbox.
- SpongeBob asks the doctor "What's the prognosis?" when he should have said "diagnosis," since prognosis is an estimate on where someone is going to end up from an injury or illness.
- When SpongeBob talks to the doctor about Squidward's "Head-go-boom-boom-itis," his eyelashes are gone for a few seconds.
- The doctor says Squidward would have Head-go-boom-boom-itis permanently if he gets one more head injury, but Squidward got many head injuries.
- When SpongeBob and Patrick yell "Squiddy!," a little bit of SpongeBob's yellow isn't there on the bottom.
- Also, his arms are gone.
- When Patrick lifts the road, Squidward is at first in front of the lifted part. However, he is under it when Patrick sets it down.
- When Patrick lifts the road to cause the truck to go airborne, the truck should have landed back on the road rather than crashing into Squidward's house.
- In a few scenes, Mr. Krabs' coloring is off.
- The same goes for Patrick in a few scenes.
- The shading in the Krusty Krab in a few scenes is off compared to other episodes of the series.
- Someone getting hit in the head (including Squidward's house).