The episode opens up with the closing of the Krusty Krab. SpongeBob leaves to go and take out the trash. When he goes around to the back of the Krusty Krab. He reads some of the dumpster writing and one of the dumpster writings says: "Krabs is a..." When SpongeBob reads the word, a Garbage Man is angry at what SpongeBob said. SpongeBob then asks Patrick what it is and Patrick says that the word is a sentence enhancer.
The next day, SpongeBob walks into the Krusty Krab and says the swear to Patrick and then over the intercom. The Krusty Krab customers are appalled by the swears said by SpongeBob and then leave. Squidward tells Mr. Krabs the story. Mr. Krabs decides to tell them that the swear is swear number 11 of a list of 13 swears (which is (very) bad luck to ones who use any of them). SpongeBob and Patrick decide to wipe the said word from their tongues and promise Mr. Krabs that they will never use it again.
Later, they play their favorite game, Eels and Escalators. Patrick gets escalators, but SpongeBob always gets eels and eventually he loses the game. After that, he utters swear number 11. Patrick then races to the Krusty Krab to tell Mr. Krabs with SpongeBob trying to stop him. During the chase, Patrick says the swear word so Spongebob starts racing faster than Patrick to tell on him. Patrick hitches a ride above an Ice-Cream Truck, but doesn't reach the Krusty Krab. SpongeBob bursts through the front door and tells Mr. Krabs that Patrick said the swear, but in a complicated way. Patrick then joins along, but they always end up changing the subject to something else.
Eventually, Mr. Krabs stops their gibberish and they say what they need to tell him. When both of them say the swear, Mr. Krabs is offended. Mr. Krabs takes SpongeBob and Patrick outside and returns with cans of paint.
Mr. Krabs is about to give SpongeBob and Patrick the job, but he hits his foot on a rock, throws the paint away and says all thirteen swears while complaining about his foot being injured and hitting the rock. When SpongeBob and Patrick hear all the swears, they run to Mama Krabs' house to tell her that Mr. Krabs all thirteen swears. When they all reach her house, they repeat the same swears during their complicated explanation. This makes her faint, but shortly after Mr. Krabs scolds SpongeBob and Patrick for saying all those bad words in front of her she regains consciousness. Mama Krabs states that all three of them should be ashamed for saying all those words in front of her and if they are going to talk like sailors, then they are going to work like sailors. She then gives all three of them the task of painting her house with a fresh coat of paint as punishment for saying those words at her. She then hits her foot on a rock too, and even though Mr. Krabs thinks that his own mother said a swear, it is actually the horn of Old Man Jenkins' car. The episode ends with all the characters laughing.
This episode became controversial as this episode teaches children the inappropriate words, even though the episodes bleeps them out so the kids don’t know what they said. The point is to deter swearing.
This episode also drew criticism from the Parents' Television Council and the fans who felt it encouraged children to use profanity. Despite this, the episode taught that it was wrong to do so and that it results in punishments: when Mr. Krabs told Patrick and SpongeBob they were using bad words, they were horrified. And, when they used them again, they were punished with painting the Krusty Krab and Mrs. Krabs' house.
"Sailor Mouth" was ranked #96 during the Best Day Ever event on November 9–10, 2006.
This episode is aired 10 days after 9/11 attack.
If one would look closely on the dumpster, you can see the words "Patchy was here." This is a reference to Patchy the Pirate.
Originally, when he lost Eels and Escalators, SpongeBob was going to say: "Go (dolphin noise) yourself!" and Patrick was to say: (dolphin noise) You too!" However, this was removed due to obvious reasons.
In the SpongeBob Squarepants Movie game, bad word number 11 is said twice in Planktopolis.
This episode was quoted to be Chris Pine's favorite episode.
It could have been Plankton who wrote the phrase on the dumpster, due to his disliking of Mr. Krabs. It could also have been a customer as Mr. Krabs is known for being a terrible businessman.
This is the second time Mr. Krabs has made SpongeBob and Patrick promise to never do a certain thing again, the first instance being Hooky.
This episode is based on the reputation of sailors to use an abundance of profanity. The episode's title is based on the term "sailor mouth," meaning someone who swears a lot. Other terms include "swearing like a sailor". Among other names are foul-mouth and potty mouth, (no relation to Potty the Parrot).
In the Brazilian dubbing, Betsy Krabs has a deep masculine voice.
Dolphin noises are heard in other episodes, but they are not used as curse words. An example would be the dolphin noises in Jellyfish Jam. Another one would be SpongeBob making dolphin noises in The Paper and You Don't Know Sponge.
When Squidward whispers the bad word to Mr. Krabs, he says: "Johnny Pantalism".
Some of the dumpster writings:
Patchy was here
Dogfish ♥s Catfish
Starfish rool (reference to Patrick)
Nematoads are people, too
Squidward smells GOOD.
Krabs is a (dolphin chirp)
When SpongeBob was telling on Patrick to Mr. Krabs it looks like he has to use the bathroom. The same thing happens when SpongeBob and Patrick tell on Mr. Krabs to Mama Krabs.
The "Squidward Smells" writing behind the green mess on the dumpster looks very simiar to the Something Smells title card both in appearance and name.
Patrick calling Mr. Krabs a "red sweaty guy" may be a reference to the season one episode Arrgh!
Squidward's quote, "Don't you mean there are only seven?" was a reference to the comedian George Carlin's infamous routine, Seven Dirty Words.
When Mr. Krabs asks, "What kind of things?" the captions say: "What things?"
When SpongeBob and Patrick are racing to the Krusty Krab it is established that SpongeBob can run faster than Patrick, except when in Life of Crime they are racing to the police station, the two are evenly matched.
When SpongeBob says: "Yea varily. Now, let's play a nice wholesome game of "Eels and Escalators." It shows the game board, but SpongeBob's left arm and the dice that SpongeBob had on his left hand are, indeed missing, while Patrick is sitting down. The next scene when Patrick says: "Oh boy, my favorite!" He is lying down, again. This maybe due to the still paint scene error.
When Mr. Krabs says: "From top to bottom." Before his right foot hits the rock, he had his teeth together because his mouth wasn't in sync with the dialogue.
When Mr. Krabs' right foot got hit, he held his left foot which was uninjured. Mama Krabs had the same error.
When Mr. Krabs pulls the penny out of Mama Krabs' pocket, it is silver instead of bronze.