- SpongeBob SquarePants
- Gary the Snail
- Patrick Star
- Squidward Tentacles
- Sam Star (debut)
- Peterson Nat Tucker (name revealed)
- King Neptune (mentioned)
The episode opens with SpongeBob and Gary sleeping. Patrick is cleaning his rock with a mop then wakes them up. 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 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. However, 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. Sam responds by getting angry and then starting to cry because she already knows it is 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. However, she uses parts of Squidward's house to decorate it, damaging it greatly. 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 head-butted by Sam along with Squidward back to their houses, damaging his house further. Squidward gets angry and drops a rock on the house, ruining the "spiffy." 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.
In the last act of retaliation, Squidward then drives a bulldozer at Patrick, Sam, and the house, trying to destroy it in a crazed rage. SpongeBob tries to stop him but to no avail. Sam, who throws the bulldozer at SpongeBob's house, stops Squidward (who suddenly disappears for the rest of the episode). 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 unconscious 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.
- Sam crushing Patrick.
- Sam pronouncing "brother" as "brubber."
|( ‣ ) Associated production music|
|( • ) Original music|
|( ◦ ) SpongeBob music|
• Coconut Cream Pie Dry - Nicolas Carr, Sage Guyton, Jeremy Wakefield [Title card]
• Skipping to School - Sage Guyton, Jeremy Wakefield [Patrick cleaning his rock]
‣ Fates - Gregor Narholz ["Nobody does."]
• Skipping to School - Sage Guyton, Jeremy Wakefield ["Hey, I'll make sure her visit here will be extra super special, no matter what!"]
‣ Clumsy A - Bernd Gesell [Big Sister Sam arrives/"Yellow square touch brubber! Make sister Sam mad!"]
• Earl's Revenge - Sage Guyton, Jeremy Wakefield [making Patrick's house bigger]
‣ Comic Capers B - Charlie Brissette, Norman Mamey [Sam pushes Squidward's house away]
• Steel Licks 10 - Jeremy Wakefield ["That oaf makes a better bulldozer than a sister!"]
‣ Harry the Hippo - Phil Green [Sam getting angry/Sam crying]
‣ Hillbilly Home - Nicolas Carr, Sage Guyton, Jeremy Wakefield ["Golly-doo-diddley, Clem, that was a nice toss."]
• Light Conversation 1 No Percussion - Nicolas Carr, Barry Anthony [redecorating]
‣ Dramatic Impact 3 - Ivor Slaney ["My house!"]
‣ Clumsy C - Bernd Gesell ["How dare you call my sister a thief, just because she took some of your things?"]
‣ Hawaiian Cocktail - Richard Myhill [Patrick cries]
‣ Dachshund Walk - John Fox, Mac Prindy [Squidward's angry]
‣ Harry the Hippo - Phil Green ["Who makes noise?!"]
‣ Lap Steel - Nicolas Carr [Squidward's house destroyed]
‣ Vibe Sting - Nicolas Carr ["Huh?"]
‣ Death and Destruction 1 - Harry Bluestone, Emil Cadkin [Squidward driving a bulldozer]
‣ Goofy Conversation - Nicolas Carr, Barry Anthony ["I think your sister's temper is getting out of control."]
‣ Down in Davy Jones' Locker - Nicolas Carr [Patrick nervous]
‣ Gargantuan - Harry Lubin [Sam destroys Patrick's house]
‣ Dramatic Cue (e) - Ronald Hanmer [Patrick unconscious]
‣ Parting of the Clouds - Nicolas Carr [shot of cookie dough]
• Aloha Lui Lui - Nicolas Carr, Sage Guyton, Jeremy Wakefield ["Patrick okay!"]
• Marlin March - Sage Guyton, Jeremy Wakefield [Ending]
- This episode is available on the Complete Seventh Season, SpongeBob and Friends: Patrick SquarePants, The Krabby Patty Recipe Theft, The SpongeBob SquarePants Collection, The SpongeBob SquarePants 8 Season DVD Collection, Patrick's Day, SpongeBob SquarePants Vol. 12, The Best 200 Episodes Ever and Next 100 Episodes DVDs.
- "Big Sister Sam" was ranked #7 during the SpongeBob's Top 100 event in the UK and Ireland from June 4-8, 2012.
- When this episode premiered it was paired up with "New Fish in Town", but since it has re-airing with "Perfect Chemistry".
- In "Something Smells", Patrick states that he doesn't have 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.
- Like in "Opposite Day" and "New Fish in Town", Squidward appears driving a bulldozer.
- This is the third episode where Patrick appears cleaning his residence. The first is "I'm with Stupid" and the second is "No Nose Knows".
- This time, he feels more eager and more prepared to meet a family member.
- This is the fourth episode where Squidward's nose comes off. The first is "Squid's Day Off", the second is "Artist Unknown", and the third is "Clams".
- This episode premiered with "New Fish in Town," but it is now paired up with "Perfect Chemistry".
- While Sam is spinning the tractor, one can see the back of her head does not have a face. However, later, it does.
- Although there are many episodes where Patrick is constantly annoying to Squidward, this is the first episode where Patrick had a bitter rivalry towards him due to caring for his sister, despite her violent and destructive nature.
- The fact that Sam mispronounces "brother" as "brubber" implies that she might have a speech impediment.
- The plot is similar to both "I'm with Stupid" and "Stanley S. SquarePants" as all three episodes involve someone's relatives.
- On November 24, 2017, this episode had a rare airing on TeenNick. This is special since SpongeBob rarely airs on TeenNick.
- At some point during this episode, SpongeBob is a darker shade of yellow.
- The first time that Sam pushes Squidward's house away, SpongeBob's house does not appear.
- When Sam "spiffs" up the house, she adds the front door from Squidward's house. The doorknob is on the right, but in a few scenes later, it is on the left.
- When Sam destroys SpongeBob's house with the bulldozer, Squidward suddenly disappears, and he isn't seen again for the remainder of the episode.
- Sam pushed Squidward's house towards the right, closer to SpongeBob's house, and it didn't seem to go very far. Later, it seemed as though Squidward's house was pushed backward, and was pushed very far back.
- In the first scene, Gary is much larger than usual. In the same scene, Patrick's house is seen to be much smaller; both Patrick and SpongeBob are taller than it. Later, in the scene when Sam arrives, the house is much larger. Throughout the episode, Sam also changes size.
- During the episode, Sam has no nails, but at the end of the episode, she says that she has to go because she's late for her manicure.
- The size of when Patrick jumps onto the sand rock and when he is on the rubble of Sam's rock is a bit different.