Stephen Hillenburg, the Creator of the show is a marine biologist, and presented his idea for the show to Nickelodeon in a bizarre way. He brought in a fish tank into the boardroom, and explained what was living inside. He then placed a cartoon drawing of SpongeBob into the tank and said "This is SpongeBob, the star of your new show."
In a 2015 interview, Tom Kenny (voice of SpongeBob) said that while recording season two, episode eighteen, "Sailor Mouth/Artist Unknown", an episode in which SpongeBob learns a bad word, the voice actors were given clearance to actually swear during recording, since it would be censored out. Whether or not an uncensored version of this episode exists, is unknown.
SpongeBob's first words when he was born were, "May I take your order?" Before this, in his mother's womb, his first words were, "Krabby Patty," and followed this by eating the same Krabby Patty his mother ate.
Spike TV approached Stephen Hillenburg to do an "adult" version of the show for their adult animation block. The show was to be similar in concept to Ren & Stimpy 'Adult Party Cartoon' (2003), Hillenburg refused to do it, and Nick refused to sell the rights to Spike TV.
Frequently, a French accented-voice comes on to note a passage of time. This is an homage to Jacques-Yves Cousteau, who was a leading influence on Stephen Hillenburg, and his interest in marine biology.
Over the years, many fans of the show have asked Tom Kenny to lend SpongeBob's voice to their voice-mail and answering machines. In an interview, he joked that these custom messages might be more common than the factory-default voice.
While Stephen Hillenburg was a director for Rocko's Modern Life (1993), he showed the show's writer, Martin Olson, a comic book called "The Intertidal Zone", that Hillenburg drew in college. Olson loved it, and suggested that Stephen re-write it as an undersea cartoon series, which became SpongeBob SquarePants.
In South Korea, SpongeBob is referred to as "Square Square Sponge", or quite often, "Square Square Sponge Song" (in the title song they needed four words to match the music and most children refer to him the second way).
SpongeBob's last name is SquarePants, but all of his relatives are round, except Stanley, who is part square, as it was revealed in season five, episode twenty, "Banned in Bikini Bottom/Stanley S. SquarePants".
SpongeBob has only played his nose as a flute three times. Once in season four, episode eight, "Patrick SmartPants", next in season four, episode twenty, "The Best Day Ever", and finally in season eleven episode twenty-three, "Old Man Patrick".
Despite being an octopus, Squidward is normally drawn with only six legs, to allow for easier animation. He is, however, shown with the correct amount of eight tentacles in the episodes "Sold!" and "Pressure".
Squidward was originally going to ink, but it was cut. He does, however, ink thrice. Once in season six, episode seven, "Giant Squidward", and secondly, in The SpongeBob Movie: Sponge Out of Water (2015), and thirdly in "The Check Up".
In season eight, episode twenty-two, "Mermaid Man Begins", it is revealed that the first names of Mermaid Man and Barnacle Boy, are Ernie and Tim, which are the names of the voice actors. Ernest Borgnine (Mermaid Man) and Tim Conway (Barnacle Boy).
Season one, episode fourteen, "SB-129", and season three, episode ten, "Krusty Krab Training Video", feature the credits on a space, and a black background, respectively, instead of the traditional underwater background.
The show, having premiered in May 1999, is the second-to-last Nicktoon of the 1990s (the last being Rocket Power (1999)). It is also the longest-running Nicktoon, spanning three decades (1990s, 2000s, and 2010s).
In season nine, episode eighteen, "The Fishbowl", Sandy's ice cream truck has the name "Pavlov" on it. Pavlov was a famous behavioral psychologist who did experiments and observations on behavior, just like Sandy does on SpongeBob and Patrick.
The voice actors for Mermaid Man (Ernest Borgnine) and Barnacle Boy (Tim Conway) also played the main characters on McHale's Navy (1962). Borgnine played Lieutenant Commander Quinton McHale, and Conway played McHale's Second in Command, Ensign Charles Parker.
A so called "banned" episode titled "Squidward's Suicide" was posted on YouTube that depicts Squidward committing suicide. The episode allegedly depicts scenes of "violence and gore", as well as quick flashes of dead children and other disturbing imagery. A story that provides background for the video, states that the episode was created in 2005, and was viewed by a select test screening at Nickelodeon. Show Writer Casey Alexander debunked the legend, saying that the episode was a "one hundred percent hoax", and was never made by the show's staff.
The signal flags hanging on the front of The Krusty Krab do not spell a word. In fact, the third signal flag (from left to right as you face the front door) does not exist in international nautical code. The first, second, fourth, and fifth are R, I, U, and K respectively, although the U is only "right-side-up" if you read the flags from right-to-left. Inside Mr. Krab's office is _, I, R, and M. The _ has no letter associated with the flag.
Clancy Brown and Bill Fagerbakke both played corrupt prison guards, though not in the same movie or television show. Brown was Captain Byron Hadley in The Shawshank Redemption (1994), and Fagerbakke was Karl Metzger in HBO's Oz (1997).
Sandy's line "We could be tighter than bark on a tree" led one internet humorist to animate a series of parodies in which this surreal expression is repeatedly dropped in amongst equally surreal characters and situations.
The trivia items below may give away important plot points.
Every time a license is seen, SpongeBob says something about a mustache (Except for when he got his Milkshake license, where he said, "If only it were this easy to get my boating license!", and laughs).
In season two, episode twenty, "Sandy, SpongeBob, and the Worm", Sandy mistakes the Alaskan Bull Worm's tongue for the actual worm, and in the end, the worm falls off a cliff. Both of these are likely references to the film Tremors (1990).