The episode opens with SpongeBob and Gary sleeping they then were woken up by Patrick who is cleaning his rock with a mop. SpongeBob asks him why he is doing it and he responds by saying his sister Sam Star, is coming. Patrick also reveals that they were lost in the surf when they were only kids.
Squidward screams angrily and demands for peace and quiet, but Sam then arrives in a bus, and punches the door down. She is revealed to be a huge starfish. Sam hugs and almost suffocates Patrick. Patrick introduces SpongeBob to Sam and Sam, mistaking SpongeBob to be a danger, protects Patrick by throwing SpongeBob. Patrick suggests that they go inside to "play", but Sam explains how the house is too small. Sam then takes a briefcase filled with sand and constructs a new house, made of sand. Patrick thanks her. But Squidward complains that his house is filled with sand. Again, Sam feels overprotective and moves Squidward's house with only her bare hands. Squidward makes jokes about Sam saying, how she is bigger, and dumber than Patrick himself. Sam responds by getting angry and then starting to cry because she already knows it's all true. Her giant tears throw both Squidward and SpongeBob.
After that, Patrick becomes overprotective of Sam by saying that SpongeBob and Squidward are "meanies" and saying that they should blecorate (decorate) the rock. But she uses parts of Squidward's house to decorate it with. Then Squidward gets angry and calls her a thief. Then SpongeBob tries to talk some sense into Patrick, but Patrick does not care that Sam deliberately dismantled Squidward's house. Then he starts crying, thinking SpongeBob has become a traitor, and gets headbutted by Sam. Squidward gets angry and attempts throws a rock at the house. In response, Sam and Patrick come out of the house and Sam chews up the loose parts and spits them at Squidward's house, completely destroying it.
Squidward then drives a bulldozer at Patrick, Sam, and the house, making Patrick and Sam realize that Squidward is literally going to kill them. SpongeBob tries to stop him but to no avail. Squidward is stopped by Sam, who throws the bulldozer at SpongeBob's house. After that, SpongeBob finally becomes upset at the destruction of his house, making Patrick finally see what SpongeBob means. Patrick tries to tell her to control her temper, but she gets very angry and destroys her own home while Patrick sacrifices himself to save the house. Patrick lays there unconcisous but SpongeBob successfully wakes him up by using cookie dough. Sam feels very guilty and explains that she must leave (She is late for a manicure and shows them her nails). As Sam leaves on the bus, SpongeBob and Patrick laugh about their experience with Patrick's sister.
( ‣ ) Associated production music
( • ) Original music
( ◦ ) SpongeBob music
• ? - Sage Guyton, Jeremy Wakefield [title card/Patrick cleaning his rock] ‣Fates - Gregor F. Narholz ["Nobody does."] • ? - Sage Guyton, Jeremy Wakefield [SpongeBob cheers Patrick up] ‣Clumsy A - Bernd Gesell [Big Sister Sam arrives] • ? - Sage Guyton, Jeremy Wakefield [making Patrick's house bigger] ‣Comic Capers B - Charlie Brissette, Norman Mamey [Sam pushes Squidward's house away] • ? - Jeremy Wakefield ["That oaf makes a better bulldozer than a sister!"] ‣Harry the Hippo - Phillip Green [Sam getting angry] ‣ ? [banjo music] ‣ ? [redecorating] ‣Dramatic Impact 3 - Ivor Slaney ["My house!"] ‣Clumsy C - Bernd Gesell ["How dare you call my sister a thief!"] ‣Hawaiian Cocktail - Richard Myhill [Patrick cries] ‣Dachshund Walk - John Fox, Mac Prindy [Squidward's angry] ‣Harry the Hippo - Phillip Green ["Who makes noise?!"] • ? - Nicolas Carr [Squidward's house destroyed] ‣Vibe String - Nicolas Carr [Huh?] ‣Death and Destruction 1 - Harry Bluestone, Emil Cadkin [Squidward driving a bulldozer] ‣ ? ["I think your sister's temper is getting out of control."] ‣ ? [Patrick nervous] ‣Gargantuan - Harry Lubin [Sam destroys Patrick's house] ‣Dramatic Cue (e) - Ronald Hanmer [Patrick unconscious] ‣ ? [cookie dough] ‣ ? ["Patrick okay!"] • ? - Sage Guyton, Jeremy Wakefield [ending]
In "Something Smells", Patrick stated "I haven't got a sister". It is possible he wanted to keep it a secret or he forgot. As mentioned by Patrick in this episode, his sister was lost a long time ago, so nobody knew about her.
In the Korean translation of Something Smells, Patrick said he had no younger sibling, so he may have meant a younger sister.
In the episode Rule of Dumb Sam should have been the so-called "Queen" of Bikini Bottom since she is older than Patrick, though she didn't appear anywhere on the royal chart. This might possibly prove that Sam is an adopted sibling.
This is the third time Patrick is shown cleaning his residence. The first would be I'm with Stupid. The second time would be in No Nose Knows. This time, he feels more eager and more prepared to meet a family member.
This somehow violates the fact that in The Battle of Bikini Bottom he disliked clean nature unless he feels that he has to be ready for a reunion.
Running Gag: Sam crushes Patrick and pronouncing "brother" as "brubber".
While Sam is spinning the tractor, you see the back of her head does not have a face. But later, it does. She must have grown it in a similar manner that Patrick made a face on his back in Survival of the Idiots.
Although there are many episodes where Patrick is constantly annoying towards Squidward, this is the first episode where Partrick had a tough rivalry toward him due to caring for his sister.
Sam may be a reference to the Incredible Hulk because of her exceeding strength and speech problems. When Sam picks up and throws Squidward's bulldozer, it is just like in the Hulk movie when Hulk throws a war tank a great distance.
Sam's two faces are a reference to Lord Voldemort in Harry Potter and the Sorcerer's/Philosopher's Stone. It is also a reference to how recent lego minifigures having double sided heads often showing different expressions.
If one would look closely when Squidward's mouth gets filled with sand, sand comes out his eyelids.
At some point during this episode, SpongeBob is a darker shade of yellow.
The first time that Big Sister Sam pushes Squidward's house away, SpongeBob's house is nowhere to be seen.
When Patrick cleans his house, he is the same size, but then he is shorter than his house.
Squidward disappears for the rest of the episode after SpongeBob's house is destroyed by the bulldozer.
When Sam "Spiffs" up the house, she adds the front door from Squidward's house. The doorknob is on the right, then in a few scenes later, it's on the left.
In this episode it is shown that Patrick has a big sister. Yet in a previose episode called, "Something Smells" Patrick says he does not have a sister.