The reason for the "N" on The Squid's shirt is because he was originally supposed to be from New York City (in the show, he had attended "Newton Elementary School" when he lived in Kansas). Word never got to the artists, so the "N" stayed.
This show was nicknamed "the show for stoners before they knew they were stoners" by several people on social media, such as Facebook and Twitter.
First episode was in 1999, and the last in 2004.
In the adult animated comedy film Immigrants (L.A. Dolce Vita) (2008), made by the same creators as this show, the character Tito is mentioned in a gag that reveals he secretly works in the prostitute business.
Came out after SpongeBob SquarePants.