SpongeBob, hoping to go jellyfishing with Patrick, finds him frantically cleaning up his home. In distress, Patrick informs SpongeBob that the following day is Starfish Day and his mother and father are planning to visit. Patrick reveals that his parents consider him to be quite unintelligent, and he can't bring himself to face their condescension. SpongeBob then offers to act like a fool so Patrick's parents will see their son as comparatively smarter.
The next day, Patrick's parents arrive. Patrick shows them inside his house, where they proceed to treat him like a child. SpongeBob soon makes his entrance, wearing his karate helmet to look more foolish and acting in a crazy manner. As Patrick's parents look upon SpongeBob's antics, they start to give Patrick a lot more credit for keeping his supposedly stupid friend in check.
At dinner, Patrick begins to lob personal insults at SpongeBob for his parents' amusement, which annoys SpongeBob. He brings Patrick to the kitchen to talk. As it turns out, Patrick has begun to forget that SpongeBob is only pretending to be an idiot, now believing himself to truly be the smart one.
SpongeBob confesses to Patrick's parents that he is not really a dummy and was only behaving like one so that they would appreciate Patrick more. This also fails, as Patrick's parents think that Patrick taught SpongeBob how to mimic basic skills such as talking in complete sentences. Their derision and laughter brings SpongeBob to the breaking point, driving him to crash through the wall in Patrick's house to get out.
Patrick's parents commend Patrick on his newfound intelligence, revealing each other to be named Janet and Marty. Patrick, confused and outraged, demands to know who these strangers are. All of a sudden, Squidward comes to Patrick's house with two other starfish, who have been asking him for Patrick all day. Patrick happily recognizes the starfish couple as his real parents, and they are happy to see him as well, especially with his pants on. Janet and Marty then remember that they don't even have a son and leave Patrick to share a laugh with his real family, just as the rock slams shut.
Apparently, Patrick has forgotten how to eat in the past as evidenced by SpongeBob saying, "Patrick! You've forgotten how to eat again! Don't worry, I'll get the funnel." Patrick informs him that is not the problem, to which SpongeBob responds, "Darn, I like the funnel." In addition, an image in "Grandma's Kisses" shows Patrick feeding SpongeBob a pumpkin through a funnel.
Marty and Janet seem just as stupid and unintelligent as Patrick is. They forgot the obvious fact that they did not even have a son, and like Patrick, they did not realize that SpongeBob was not dumb when he admitted it.
This is one of the few times a math equation (2+2=4) is shown within the SpongeBob SquarePants universe. Another example is shown in "SpongeHenge" with calculus.
This episode marks the first appearance of Patrick's furniture made out of sand.
In Croatian dub, the episode name is "Tko je Glup?" or "Who is Stupid?"
The scene where Patrick goes "Huehuehuehuehueh!" has become a popular internet meme.
Patrick mistakes the word "genius" for "genies," thinking that "genius live in lamps." However, in "Christmas Who?" he says the word genie correctly.
In Indonesia, instead of saying, SpongeBob says “Patrick! You forgot how to eat again! Come on, we'll get the funnel.," SpongeBob says “Patrick! You forgot how to clean your ears again, don't worry we'll get the stick.”
When SpongeBob turns over the note, a 16th note can be seen. When he turns over the letter, the letter B can be seen.
In the Malaysian version, the beginning of this episode starts with Patrick saying out the alphabets instead of Patrick cleaning his house.
Marty appears to have knowledge of an electrician, as shown by his quotes as follows:
After SpongeBob makes electrical buzzer noises, Marty asks Patrick if SpongeBob is "broken."
When SpongeBob is tensing up when he is fed up with Marty's bullying, he says "Oh now he's short-circuiting!" and that "because Patrick taught him too much!" "Short-circuiting" is a term used when a low-resistance circuit is flowing current far too quickly, making the battery heat up far too quickly, which Marty references.
After SpongeBob runs off annoyed, Marty talks about Patrick's brightness being a "3-watt [lightbulb]," while he says SpongeBob's brightness makes "phone operators seem smart."
Coincidentally, Thomas F. Wilson is also known for playing Biff in the 1985 film, Back to the Future, while the protagonist of the film was named Marty McFly.
When SpongeBob runs into his house as a portrayal of his stupidity, Squidward's house is not there. When Patrick, Janet, and Marty are talking by SpongeBob’s pineapple house, Squidward's house disappears again.
When Marty, Patrick, and Janet are watching SpongeBob doing various things, there is a table with dinner. After Marty says that SpongeBob might be broken, the table and the food disappear.
When SpongeBob and Patrick were talking in the kitchen, after SpongeBob sad "Patrick, I get the feeling that you think I really am dumb," Patrick is wearing the "I'm with the Dummy" shirt, but when Patrick is in the next scene, the shirt is gone.
When Patrick's fake parents are at his house, there is a complete kitchen and living room with sand furniture. At the end, where Patrick's real parents are laughing with him, the space under the rock is completely empty.
There is an error in the closed-captions for this episode; when Patrick is mocking SpongeBob by shouting: "I'm ready, I'm ready, I'm ready!" the captions display it as "Harmony, harmony, harmony!"
Marty was standing on the left side of Patrick and Janet was standing on the right side of Patrick. However, when they patted him, his arm was on the right side and her arm was on the left side.
Even though Marty and Janet were not Patrick's parents, they somehow knew his name. It is likely that they knew him before the episode.
SpongeBob should have already met Herb and Margie Star because he and Patrick have been friends since they were babies.
When SpongeBob is mad at Patrick, Marty, and Janet (thinking he is a moron) he escapes by breaking the wall. The background seen from the hole is the sky; however, Patrick's house is set underground. The same mistake also occurs in "Night Light."
The sound of a doorbell can be heard when Patrick's "parents," SpongeBob and Squidward all show up at Patrick's house. However, Patrick's house doesn't have a doorbell.