WHAT IS THE MOST UNIQUE SONG THAT YOU HAVE EVER HEARD?

Anything by the Dixie Dregs

Anything by Stimmhorn, or it' s vocalist, Christian Zehnder  https://youtu.be/-UsjZYzryVU

Every song on Van Dyke Parks' debut album Song Cycle will sound odd to most listeners, none more so than "The All Golden." You think Syd Barrett sounds unusual?!

After you listen to Song Cycle, go back and listen to Smile. You will then hear how much VDP influenced Brian Wilson musically in 1966 and 7. Smile was really a collaboration between the two, too good to be reduced to a mere Beach Boys album. Mike Love could barely deal with Brian's musical wisdom; Van Dyke's was just too much for him.

Aja by Steely Dan
Almost everything in non conventional but it melds together beautifully! Many time changes and melody changes is confusing and still so intriguing! I have it on LP Mobile Fidelity so it sounds incredible on my system!

Timothy - The Buoys. Although there may have been other songs about cannibalism, I don't believe any other one made it to the top 20 on Billboard as did Timothy. Trivia note: It was written by Rupert Holmes, famous for Escape (The Piña Colada Song) and he played piano on Timothy.
Honorable mention: Can't believe no one mentioned Bohemian Rhapsody by Queen. Very unique in its day and made it into the top 10 twice in two different decades.