- Gary the Snail
- SpongeBob SquarePants
- Cowboy fish (cameo on TV)
- Frankie Billy (blue)
- Jan the Worm (cameo)
- Eugene H. Krabs
- Monroe Timmy
- Nudibranch (debut)
- Puffy Fluffy (debut)
- Nudibranch seller (debut)
- Jellyfish (cameo in painting)
- Grandma SquarePants or Grandma BubbleBottom (mentioned)
- T.S. Halibut (mentioned)
The episode opens on SpongeBob's house. The scene cuts to the inside, where SpongeBob is about to feed Gary. The food drops from the can into Gary's food bowl then Gary starts to eat it. SpongeBob throws the can into the trash, but it is overfilled with cans of snail food, so the can he throws causes other cans to fly out of the pile on top of the can. The can then hits the stove, where it knocks two cans off the stove. It then goes to the overfilled sink and makes dirty dishes fall. Finally, it cuts a rope and causes a shelf to go down and a barrel, which was on top of a box on the shelf, to start rolling. The barrel hits SpongeBob, knocking him out of the kitchen. SpongeBob lands in the living room and the barrel rolls away. The can then lands on SpongeBob's nose. Gary enters the living room and "meows."
SpongeBob gets up and throws the can behind him. SpongeBob tells Gary, "I'll get out of your hair," and pets him. SpongeBob pushes his nose and his Krusty Krab employee hat moves from inside him to the top of his head. SpongeBob opens the door and tells Gary, "See you later, Gare." He looks down and sees Gary with his leash. SpongeBob thinks Gary wants to go on a walk but says that he does not have time for a walk because he has to get to work. He also tells Gary that he will have to stay home. He then promises that as soon as he gets home, they will have fun. While leaving, SpongeBob tells Gary that he loves him and says, "Bye."
Once SpongeBob is gone, Gary uses the leashes like a lasso and opens a cupboard and gets a can of chips. He then moves the chips to the chair. He grabs a cowboy hat with drinks attached to it from the fish lure on the wall. He moves that to the chair and then, holding the remote, sits down in the chair. He manages to get to the chair before the hat lands, so it lands on his shell. Gary turns on the TV, which is on a cowboy movie or show.
Outside, SpongeBob, still at his house, thinks that Gary is lonely and says, while walking away, "I can only imagine the tortured loneliness that he must be feeling right now." The scene cuts to Gary laughing at the cowboy movie or show.
Later, at the Krusty Krab, SpongeBob is sweeping next to Fred, who is about to eat his Krabby Patty. Fred gives SpongeBob an angry look because SpongeBob is kicking up so much dust. SpongeBob stops when he hears the doors open. He starts to greet the new customer but stops when he notices that the customer has a worm. SpongeBob tells the customer that they have a "no pets" policy and that the worm will have to wait outside. Frankie Billy (the customer) says that he could not do that because his worm gets far too lonely and upset when he is left alone. Frankie Billy tells his worm that he cannot buy the Krabby Patty that the worm wanted. Frankie Billy tells his worm that they are going home. The two walk to the exit, but are stopped by Mr. Krabs who tells Frankie Billy that the two can get two Krabby Patties at regular price. He then walks the two to SpongeBob, who is sweeping. Mr. Krabs tells SpongeBob to give the responsible pet owner two Krabby Patties. SpongeBob gets sad because of the word, "responsible" and remembers Gary, who he thinks is suffering. He explains that he leaves Gary home by himself every day. He says that he better call to make sure that he is okay.
At the pineapple, Gary is still watching the cowboy movie and clearly having a good time and is in no way lonely or sad at all. The phone rings, but Gary is too distracted to pick up.
Back at The Krusty Krab, SpongeBob thinks that Gary is too distraught to pick up the phone. SpongeBob then hears his voicemail message, which features SpongeBob saying, "Hello. You've reached SpongeBob and... come on, Gary..." and Gary meowing. Voicemail SpongeBob continues saying, "...and Gary. The two of us are having too much fun together to answer the phone right now, so leave a message and we call you right back if we ever take a break from having so much fun... together." SpongeBob and Gary then laugh. As the message goes on, SpongeBob gets sadder and sadder. He says that his message is a lie. He then leaves a message asking Gary if he is there and that he is just checking on Gary. Gary is laughing at the movie or show again. At the end of the message, SpongeBob says that he will be home soon.
At night, SpongeBob turns the "open" sign to "closed." He takes off his hat and sneaks out the front door. He gets caught by Mr. Krabs. Mr. Krabs is starring the parking lot and wants SpongeBob's help. SpongeBob says that he cannot because he has a lonely pet snail to get back to. Mr. Krabs tells SpongeBob that he can go as long as he comes in five hours early to finish the parking lot the next day.
Later, while running home, SpongeBob wonders how he can balance being a pet owner and having a job. SpongeBob passes a cart that is selling nudibranchs. At the cart, Fred and Monroe Timmy are buying one. Monroe Timmy asks Fred if it is his. Fred says that it is. He also says that now Monroe Timmy has a furry friend to keep him from feeling lonely. SpongeBob overhears this and stops. Fred continues saying that he can go on his business trips without feeling guilty. SpongeBob thinks that if he gives Gary a friend, he will not be lonely. Fred and Monroe Timmy walk away and SpongeBob runs up to the window of the cart. He sees the nudibranchs and calls them, "precious." He chooses a green one. The seller says, "You wish to obtain my rare and extremely dangerous..." She is cut off by the fact that SpongeBob has entered the cart and picked out the one he wants. She turns to SpongeBob and warns him that the nudibranchs don't like other pets. She shows a picture of a cat to one of the nudibranchs and it starts to get angry. SpongeBob leaves the cart with the nudibranch, thanking the seller. She wonders why she even warns people when they never listen.
Later, at the pineapple, on the TV, the cowboy movie or show is still showing. The Cowboy fish tells the sheriff that he has met the bank robber. He throws the hat on the table and says that the hat is the bank robber, so the sheriff should cuff him. SpongeBob interrupts the scene. Gary is surprised, which makes the hat fly off his head. Gary is then disappointed. SpongeBob says that he has bought a new playmate for Gary. SpongeBob sets the nudibranch next to Gary and says that he is named, "Puffy Fluffy" and that he will be keeping Gary company while SpongeBob is at work. SpongeBob says that he will leave Gary and Puffy Fluffy alone to get to know each other while he gets something. Gary meows and Puffy Fluffy roars revealing giant, sharp teeth. SpongeBob returns with food for Gary and Puffy Fluffy. Gary goes to his bowl and is about to eat when SpongeBob stops him. SpongeBob then scolds Gary about not having manners in regards to not sharing while he adds, "/Puffy Fluffy" to Gary's bowl. SpongeBob moves Puffy Fluffy from the chair to the bowl. SpongeBob tells them to eat up while he makes some enchiladas. Puffy Fluffy roars, scaring Gary away. He then proceeds to eat the entire bowl with the food. Puffy Fluffy scoots over to Gary, who is hiding behind the TV. He hears SpongeBob say, "I'm back," so he stops what he is doing.
While walking to his chair, SpongeBob comments how the enchiladas are hot. SpongeBob thinks that Gary's cowering is that he is ignoring Puffy Fluffy, so he takes the two and puts them next to toys so that they can play together to bond. When SpongeBob gets back, he comments on how his enchiladas are cold. Gary chews on the carrot chew toy. Puffy Fluffy roars, which makes the chew toy fall out of Gary's mouth. Puffy Fluffy shreds the toy while SpongeBob begins to eat his enchiladas. Puffy Fluffy tries to bite Gary, but he runs out of the way. He lands on SpongeBob, making him drop his enchiladas. SpongeBob comments on this fact. He also says that because of this and he will not cooperate with Puffy Fluffy, he is putting Gary to bed early.
Later, still in the living room, SpongeBob puts Gary and Puffy Fluffy in a bed together. He puts a blanket on the two and notices how cute they are together. Gary apologizes and SpongeBob accepts his apology and tells the two, "good night." When SpongeBob leaves, Puffy Fluffy roars again.
In SpongeBob's room, he is also going to bed. SpongeBob says that he is going to sleep well knowing that Gary has a playmate to spend time with. He then starts sleeping. Gary runs into the room, waking SpongeBob. SpongeBob takes Gary back downstairs and shows Gary that Puffy Fluffy is harmless by showing Gary that he is fast asleep. SpongeBob puts Gary back in the bed, turns off the light, and goes back upstairs. "Puffy Fluffy" deflates revealing that it was not him. Gary is surprised and hears a noise coming from the kitchen. There he sees a Puffy Fluffy as a monster, digging through the refrigerator. He roars at Gary and he is scared.
Meanwhile, SpongeBob, fast asleep, turns to his side. Back in the kitchen, Gary gets onto the stove and takes one of the pans that is hanging up to use a weapon.
Meanwhile, SpongeBob, still fast asleep, turns to his other side. He also mumbles in his sleep.
Back downstairs, Gary begins running from the beast, who chases after him. Gary enters the library. Puffy Fluffy has Gary up against a bookcase, but Gary manages to escape, making Puffy Fluffy lunge into the bookcase, which causes books to fall down. A stack piles on top of Gary. He pops his eyes out and Puffy Fluffy then chases him around the book pile, accidentally hit the fire log into the pile of books, creating a fire that begins to spread to the surrounding books. This causes a fire border between Gary and Puffy Fluffy.
Meanwhile, back with SpongeBob, smoke begins to seep through the cracks in his door to the library. Still sleeping, SpongeBob smells the fire and thinks that his grandma is making meatballs.
Meanwhile, in the bathroom, Gary is trying to put out the fire by using water from the bathtub. He manages to do so. He sees that Puffy Fluffy is digging through SpongeBob's library closet. He leaves with a pair of SpongeBob's pants and rips them up. Gary then begins to bite Puffy Fluffy. Puffy Fluffy hits Gary off his back, making him hit a bookcase, making a few more books fall. Gary makes Puffy Fluffy hit the bookcase again.
Back in SpongeBob's room, the ceiling starts to fall apart, while SpongeBob remains sleeping.
Meanwhile, Gary has managed to make it to the garage, where he ends up at a wall. Puffy Fluffy lunges at Gary.
A loud rumble is heard in SpongeBob's room. He wakes up a bit but manages to get back to sleep.
Gary leaves to the living room, through a hole in the wall. Puffy Fluffy follows and chases Gary through the house until morning.
SpongeBob's alarm goes off while more of the ceiling falls. He wakes up. He says that he better check up on Gary and Puffy Fluffy. SpongeBob notices the fallen parts of the ceiling and thinks that there was a seaquake. He then opens the door to the library. The door falls off. He then sees the ruined library. He slides down the slide and then notices that his Memories of T.S. Halibut book is ruined. He then notices that his clothes are ruined. He realizes that it was not a seaquake and wonders who could have done so much damage. He then thinks that Gary did this out of jealousy. He then heads down the stairs, angrily. He tries to open a door, but it is locked he angrily asks Gary to open it.
Meanwhile, in the exercise room, Gary is about to be eaten by Puffy Fluffy. SpongeBob then opens the door by force. He then sees that Gary is being eaten by Puffy Fluffy. However, instead of rushing to Gary's rescue, SpongeBob scolds him, telling him to put Puffy Fluffy down—even when Puffy Fluffy is clearly trying to eat the snail, and Gary is yelling in agony. Puffy Fluffy then puts Gary down and takes SpongeBob instead. Gary then sees that SpongeBob is in trouble and grabs his cowboy hat and lasso. He then whips Puffy Fluffy with the lasso. He then lassoes Puffy Fluffy's monster tongues and this makes Puffy Fluffy run out of the house and into the distance. SpongeBob runs out of the house, begging for Puffy Fluffy to come back, to no avail. SpongeBob then looks at Gary and ungratefully scolds him again, demanding to know what he has to say for himself.
Later, at the Krusty Krab, SpongeBob enters the kitchen, holding Gary, saying that he will take Gary where ever he goes and that Gary will no longer be alone. Mr. Krabs asks what Gary is doing in the kitchen. SpongeBob says that he is bringing Gary into work and then gives Gary a Krusty Krab employee hat. Mr. Krabs likes the idea of free labor. He then asks Gary to serve up some Krabby Patties, handing him a spatula. Gary meows in a disappointed tone.
|( ‣ ) Associated production music|
|( • ) Original music|
|( ◦ ) SpongeBob music|
‣ Clownfish Capers - Sage Guyton, Jeremy Wakefield [title card]
‣ Skipping to School - Sage Guyton, Jeremy Wakefield [opening]
‣ Grass Skirt Chase - Sage Guyton, Jeremy Wakefield [Gary grabs everything he needs to watch TV]
‣ Unknown Track 56 - Gary turns on the TV
‣ Steel Sting (q) - Jeremy Wakefield ["Poor little snail."]
‣ Unknown Track 56 - Gary watching TV
‣ Botany Bay - Michael Bolger, Nicolas Carr [at the Krusty Krab]
‣ Steel Licks (b) - Jeremy Wakefield [no pet policy]
‣ Drama Link (d) - Hubert Clifford ["Eh?!"]
‣ Sailor's Sting 4 - Michael Bolger, Nicolas Carr ["Hey, let's not be hasty."]
‣ Steel Licks (c) - Jeremy Wakefield [SpongeBob feels guilty]
‣ Unknown Track 56 - Gary still watching TV
‣ Steel Licks - Jeremy Wakefield [SpongeBob calls Gary]
‣ Unknown Track 56 - "Hello. You've reached SpongeBob and...C'mon Gary"
‣ Unknown Hawaiian Sting (e) - Jeremy Wakefield [SpongeBob leaves a message]
‣ Unknown Hawaiian Sting (z) - Jeremy Wakefield [If we ever stop having so much fun, together!]
‣ Unknown Track 56 - SpongeBob leaves a message.
‣ Steel Sting (f) - Jeremy Wakefield [SpongeBob puts the phone down]
‣ Slinky Panther Pants - Nicolas Carr [closing time]
‣ Sailor's Sting 12 - Michael Bolger, Nicolas Carr [Krabs re-tarring the parking lot]
‣ Steel Link (c) - Jeremy Wakefield ["Poor Gary's been home alone all day."]
‣ The Pollywog Strut - Nicolas Carr, Barry Anthony ["Wow, Dad, is it really mine to keep?"]
‣ Why Am I So Poor? (b) - Laszlo Borteri [SpongeBob buys another pet]
‣ Unknown Track 56 - Gary still watching TV
‣ Cartoon Sting 1 - "I brought you a surprise!"
‣ Tales from the Swamp (c) - Ron Goodwin [Puffy Fluffy roars at Gary]
‣ Cartoon Sting 1 - "Eat up, you two."
‣ Jarabe Tapatio (a) - Gerhart Frei, Carlos Periguez ["I'm gonna make some enchiladas."]
‣ Unknown Track 53 - Ron Wasserman [Puffy Fluffy eats the entire food bowl/Puffy Fluffy rips the squeaky carrot toy.]
‣ Lap Steel - Nicolas Carr ["I hope you're happy now."]
‣ Finger of Fear - Fredric Bayco [Gary has to share his bed with Puffy Fluffy]
‣ Solo Steel 4 - Jeremy Wakefield [SpongeBob goes to bed]
‣ Drama Link (f) - Hubert Clifford [Gary enters]
‣ Rock-a-Bye Baby - "See? There he is, fast asleep."
‣ Drama Link (c) - Hubert Clifford [balloon deflates]
‣ Cellar Search - Philippe Pares [Puffy Fluffy's grown to gigantic size]
‣ Unknown Track 53 - Ron Wasserman [Puffy Fluffy roars at Gary/Gary tries to defend from Puffy Fluffy.]
‣ Lullaby Box - Leo Nissim [SpongeBob talking in his sleep]
‣ Abject Terror - Paul Lewis [Puffy Fluffy chases Gary]
‣ Stealth by Night - Jack Coles ["Mmm, you're making meatballs, Grandma?"]
‣ Sword Fight - Harry Bluestone, Emil Cadkin [Gary putting out the fire]
‣ Vibe Q Sting - Nicolas Carr ["Huh?"]
‣ Alone in the Old House - Gregor F. Narholz [SpongeBob's library destroyed]
‣ Terror - Alan Braden [Gary's about to be eaten]
‣ Sword Fight - Sam Fonteyn [SpongeBob breaks down the door]
‣ Tales from the Swamp (a) - Ron Goodwin ["Gary!"]
‣ Horror House of Wax Retro 2 - Nicolas Carr, Ron Wasserman [Puffy Fluffy tries to eat SpongeBob]
‣ Unknown Track 56 - Gary saves SpongeBob
‣ Sailor's Sting 1 - Michael Bolger, Nicolas Carr [ending]
- As of July 27, 2017, The Internet Movie Database (IMDB) gives this episode a rating of 3.4/10 based on 304 ratings by users. TV.com users give this episode a rating of 7.1/10 based on 155 votes.
- This episode, along with "Keep Bikini Bottom Beautiful," has the lowest IMDb rating of any SpongeBob SquarePants episode. 
- Running gag: Puffy Fluffy attacking Gary when SpongeBob leaves a room.
- The title card background for this episode is very similar to that of "Culture Shock," the only difference being that the title card for the latter is a lighter shade of red.
- The same title card is also used in "Mimic Madness," except, similar to "Culture Shock," the episode uses a lighter shade of red, however it is widescreen, unlike "Culture Shock" and "A Pal For Gary."
- In real life, nudibranchs (sea slugs) are worm-like creatures. However, in this episode, they are portrayed as fluffy fish. (This is until Puffy Fluffy turns into a vicious monster.)
- Puffy Fluffy tries to eat SpongeBob, which is appropriate since real nudibranchs eat sponges.
- There is an online game based on this episode called Gary's Revenge, which itself is based on the game Angry Birds.
- This episode features a phone that is not a shellphone.
- This is the second episode where Gary wears a Krusty Krab employee hat, the first being "Banned in Bikini Bottom."
- This episode reveals that the garage in SpongeBob's house is located behind the living room.
- In the Polish dub of the episode, SpongeBob tells Puffy Fluffy to put Gary down, unlike in the original version.
- In the German version, this episode is called "Spielkamerad des Grauens," or "Playmate of Horror.
- This episode was paired up with "Don't Look Now" On the Massive Monster Mayhem Marathon.
- The theme of getting a pet from a mysterious old person that is potentially dangerous, a cute creature becoming a monster, and a good pet destroying the monster parodies Gremlins.
- The container for the chips that Gary eats is similar to the Pringles cans.
- The episode's title is a possible pun on "appall for Gary" and its literal meaning, which makes sense, considering that the pet is given is considered by most people as horrifying (synonym for appalling).
- T.S. Halibut may be a possible reference to British essayist T.S. Eliot.
- Throughout most of the movie or TV show, the cowboy fish is his normal design, but in the last scene that is shown, he is purple with a blue fin.
- When SpongeBob is walking away from his house near the start of the episode, his belt turns white for a split second. There is a similar mistake in "Boating Buddies."
- It is unknown why the fire log is lit in SpongeBob's library when is sleeping in his bedroom and there is nobody to watch over it.
- Mr. Krabs tells to come in five hours early at work, so he should have woken up at 4 a.m. instead of 9 a.m.
- SpongeBob calls the book Five memoirs of T.S. Halibut, but the cover says Memories of T.S. Halibut.
- Squidward and Patrick's houses are missing from the scene where Puffy Fluffy runs off into the distance away from SpongeBob's house.