In Encino, California, the French Narrator introduces the president of the SpongeBob SquarePants fan club, Patchy the Pirate. He is a live-action character who is currently preparing for Christmas, and his "pet," Potty the Parrot, a crudely made puppet with very obvious strings. Patchy shows two pictures of SpongeBob & Patrick, which fades to first: SpongeBob's Christmas setup and second: Patrick's rock with a tree ornament on it. Patchy receives a fan letter from a person whose name and address is withheld, asking if SpongeBob likes Christmas as much as he does. Patchy explains that they didn't always celebrate Christmas in Bikini Bottom, and decides to show how they were introduced to it, beginning the proper episode.
At Sandy's Treedome, Sandy is putting up Christmas lights. SpongeBob, who is in his karate gear and preparing to attack her, mistakes it for a fire, and then rushes inside, throwing water onto it. Sandy asks him what he was doing, and SpongeBob replies he believed there was a fire. Sandy is shocked that SpongeBob has never heard of Christmas, and tells him all about it.
Later, at the Krusty Krab, SpongeBob tells Patrick, Squidward and Mr. Krabs about Christmas. Everyone in Bikini Bottom, except Squidward, believes him, and they all, except Squidward, put their Christmas wishes into bottles, which are then shot up to the surface so Santa can read it. In the days leading up to Christmas, the people of Bikini Bottom heartily celebrate, and on Christmas Eve, stand in front of the large decorated coral tree and sing, eagerly awaiting the arrival of Santa. Meanwhile, Squidward, refusing to believe in Christmas, is wanting no part of it. The people continue to sing until morning, when Santa has failed to arrive (which was much to SpongeBob's dismay).
Everyone leaves and SpongeBob becomes very depressed. Squidward appears, laughing and scoffing at his humiliation, and takes a photo of the heartbroken SpongeBob. As he sulks away, he gives Squidward a present. Squidward, now feeling sorry for SpongeBob, opens it, and finds a handmade driftwood clarinet. He now realizes that he is a "big jerk" and his grouchy attitude had ruined Christmas for everyone. To make it up to SpongeBob, he dresses up as Santa. SpongeBob was very delighted and thanks "Santa" for bringing Christmas to Bikini Bottom. Squidward tells SpongeBob that Santa didn't bring Christmas to Bikini Bottom, but he did. SpongeBob passes out from joy, and Gary carries him home.
Squidward prepares to take the costume off, but is confronted by a little girl, asking him for a present. SpongeBob suddenly appears beside her, assuring her that he will. Out of desperation, Squidward gives the child a wrench from his house. He then sees a crowd of people, who want their gifts as well, and ends up giving away everything he owns. Afterwards, Squidward finds a message from Santa on his doorstep, thanking him for his help and telling him that he's been a "good boy." He then sees the real Santa Claus (Live action character) riding away in his sleigh. The dumbfounded Squidward says "Yep. I'm insane." and goes back inside, playing his new clarinet.
After the SpongeBob episode ends, Patchy's house is seen again. Potty gives Patchy a little present. Patchy steps under a mistletoe, hoping to be kissed by a woman, only for Potty to start chasing after him with the intention of kissing him. Seeing that Patchy is busy at the moment, the narrator said "Goodnight, and Happy Holidays." for Patchy.
"It's a SpongeBob Christmas!" premiered on Nickelodeon exactly 12 years after this episode aired.
This is the first episode to show Patrick with his one tooth (when he says "just like a genie"). Patrick's single tooth would later appear in more episodes and heavily used in season 5 episodes.
This is the second time Squidward feels guilty about bullying SpongeBob and apologizes to him. The first was in "Fools in April."
This is the third episode where SpongeBob, Patrick, Squidward, Mr. Krabs, Sandy, Plankton, and Gary (the main characters) all appear in the same episode. The first was in "Culture Shock" and the second was in "Sleepy Time."
On the Season Two DVD, Patchy's line at the beginning of the second half of the episode, "It's about time you got back! (Holds up a SpongeBob Christmas decoration) Now I can finish me story! (Scene cuts close to the decoration)," is cut due to there being no commercials on the DVD.
When the fish were sending their letters to Santa, one fish said "I hope he can read Portuguese." However, it is unknown if he was heard speaking that language from Portugal.
In the Brazilian dubbing of this episode, the dialogue "I hope he can read Portuguese" was changed to "I hope he can understand my calligraphy," because Portuguese is the language spoken in Brazil.
The music on the record player that Squidward has while he pretends to play with his clarinet, is the same song he played in "Bubblestand."
The reason Santa didn't come to Bikini Bottom is because the citizens didn't go to sleep on Christmas Eve, and it is said that Santa only comes when people are asleep. However, a later episode "It's a SpongeBob Christmas!" contradicts this fact.
It is rather odd that Squidward had a Santa suit, as Christmas was only introduced the day before. This seems to imply that Squidward made the Santa suit himself.
When Squidward feels guilty for bullying SpongeBob, he says "I feel like a..." and a picture of a donkey appears. This is a subliminal message that Squidward feels like a donkey. A similar instance of this joke being used is in "Fools in April."
Squidward saw Santa on his sleigh at the end, but it should be impossible for Santa to be able to breathe underwater. This could be why Bikini Bottom never heard about Christmas (Except Sandy, since she is a land animal).
And, instead of him singing the opening, a female chorus sings the intro. Also, the logo card was changed to a Christmas title card.
In the Polish dub, the episode's title is "Jakie święta?" translating to "What Christmas?"
In the Croatian dub, the episode name is "Božić, što je to?" translating to "Christmas, what is that?"
In "Jellyfishing" when Squidward came home Patrick yelled "Merry Christmas!" but he did not know what Christmas was until this episode. This seems to suggest that "Jellyfishing" took place after this.
This episode most likely took place before "Sandy's Rocket" since SpongeBob wore a Santa hat to bed in that episode, which indicates that Christmas had already been brought to Bikini Bottom by the time of that episode.
SpongeBob and Patrick don't know Christmas in this episode, however, in "The Secret Box," Patrick hides an embarrassing photo of SpongeBob at a Christmas party. A possible reason for this is that this episode may have took place before "The Secret Box." Also, "The Secret Box" was made and aired after "Christmas Who?"
This episode takes place after "Single Cell Anniversary" because in that episode Plankton did not know how to sing a song while in this episode he already knows how to sing.
This is the last episode where Nancy Suzy Fish is seen with nostrils.
A little girl told SpongeBob that she wanted front teeth for Christmas. This is a reference to the song "All I Want For Christmas is My Two Front Teeth."
The title is a later reduction on the holiday film Santa Who?.
At the beginning, it was sunset, but when Sandy plugs in her tree, it is suddenly night.
Sandy was seen putting up Christmas lights at the beginning, even though she hibernates in winter. In "Bubble Buddy," Sandy does hibernate during Bikini Bottom's spring, so when it was winter in Bikini Bottom, it was still autumn for Sandy, therefore it was not time for Sandy to hibernate.
It's possible that Sandy didn't want to hibernate through Christmas.
Towards the end of the sequence where Sandy was telling SpongeBob about Christmas, bubbles were shown when she was moving. This is impossible, as they were in the air filled treedome.
A few seconds after Patrick says "Like a Genie," his eyebrows turn red for a split second as he blinks.
When SpongeBob gave Patrick his second sheet of paper, his black shoes are transparent.
The girl who asked for front teeth are crossed eyed in one scene.
During the song, where they are showing Squidward his new decorated house, SpongeBob's house next-door is missing.
When Mr. Krabs gives Plankton the fruitcake, it is sunset in the evening. However, when the fruitcake lands in the trash, it is instantly night.
At first, Patrick was on the coral tree but when it was daytime, he wasn't there anymore. Patrick must've fallen off the tree.
When Squidward (dressed as Santa) was talking to SpongeBob, his eyelids briefly changed color for a split second to a lighter teal.
When SpongeBob said "Where's your reindeer, and your flying machine?" Squidward had two legs instead of four.
Harold's white shirt and shorts turn black in a few scenes.
SpongeBob's tie is invisible in the sequence leading up to the picture being taken, and in the physical picture.
The photograph that Squidward took when SpongeBob was crying due to the fact of Santa not coming has multiple errors, when Squidward holds the photo the background around it is sand instead of snow; in the photo, the background is not the winter sky or snow, it is the typical sky that is seen in the other episodes, even though the coral tree is still visible. SpongeBob's tie is also invisible, possibly from the drooping nose.
Although Santa traditionally has 8 reindeers, (9 counting Rudolph) only 4 are seen or possibly the other four are next to the four seen.