Multiple mispellings refer to the correctly spelled word "Supercalifragilisticexpialidocious" - a nonsense word uttered by the character, Mary Poppins in the 1964 movie of the same name. The Walt Disney production of the film, starring Julie Andrews as Mary Poppins, featured the word in a song that tells how you can use it to impress others or as an exclamation when you don't know what to say. (The movie, Mary Poppins, was based on the book of the same title, written by P L Travers in 1934.)
(lyrics from the song's chorus)
Even though the sound of it is something quite atrocious,
if you say it loud enough you'll always sound precocious.