I would put this word on my list of words that inflict excruciating pain, but in the interests of logology (and orthography) herewith a paste from the OED:

Made popular by the Walt Disney film ‘Mary Poppins’ in 1964. The song containing the word was the subject of a copyright infringement suit brought in 1965 against the makers of the film by Life Music Co. and two song-writers: cf. quots. 1949, 1951. In view of earlier oral uses of the word sworn to in affidavits and dissimilarity between the songs the judge ruled against the plaintiffs.

1949 Parker & Young (unpublished song-title) Supercalafajalistickespialadojus. 1951 I (song-title) Supercalafajalistickespeealadojus; or, The super song. 1964 R. M. & R. B. Sherman (song-title) Supercalifragilisticexpialidocious! 1967 Decisions U.S. Courts involving Copyright 1965–66 488 The complaint alleges copyright infringement of plaintiff's song ‘Supercalafajalistickespeealadojus’ by defendants' song ‘Supercalifragilisticexpialidocious’. (All variants of this tongue twister will hereinafter be referred to collectively as ‘the word’.)