I believe that the "lyrics" came about as a result of them having a tune ready for recording, which happened to coincide with them suddenly becoming stricken with a severe bout of "group lyric mental-block syndrome". In the now absent ability to formulate known words to fit the tune, they had to resort making up vocal noises instead of using real words in order to release the record without further delay. As they had not only dared to do this, but also managed to perform the "song" live without collapsing into gales of laughter at the success of their musical con, the song became regarded, in some quarters at least, as something of an avant garde piece. For me, the strangest fact is that, devoid though the song is of real lyrics, almost everyone who was around during that era, myself included, can sing along with the song "word" perfectly to this day!?!?