More about
the lyrics

Pink Elephants on Parade is the name of a segment, and the song played therein, from the 1941 Disney animated feature film Dumbo in which Dumbo and Timothy Q. Mouse, after accidentally becoming intoxicated (after drinking water spiked with champagne), see pink elephants sing, dance, and play marching band instruments during a hallucination sequence. After the sequence, Dumbo and Timothy wake up, hungover, in a tree. It is at this point that they realise that Dumbo can fly.

Drunken pink elephants have no place in a childrens' movie, but they provide the key moment in the best animated film of all time.
-- The Guardian

Authors

The song was written by Oliver Wallace and Ned Washington and sung by Mel Blanc, Thurl Ravenscroft and The Sportsmen. The segment was directed by Norman Ferguson, laid out by Ken O'Connor and animated by Hicks Lokey, Frank Thomas and Howard Swift.

Meaning of seeing pink elephants

“Seeing pink elephants” is a euphemism for drunken hallucination caused by alcoholic hallucinosis or delirium tremens. The term dates back to at least the early 20th century, emerging from earlier idioms about snakes and other creatures. An alcoholic character in Jack London's 1913 novel John Barleycorn is said to hallucinate “blue mice and pink elephants”.

References

Pink elephants on parade | Wikipedia EN

Why I love Dumbo's pink elephants | The Guardian

Pink Elephants on Parade - lyrics | Genius

Seeing pink elephants | Wikipedia EN