pink elephant

plural pink elephants

1. informalA stereotypical hallucination, particularly one brought on by drinking alcohol.

   I remember lying by the side of the road watching the pink elephants dancing by.

   1 more example

   There are, broadly speaking, two types of drinkers. There is the man whom we all know, stupid, unimaginative, whose brain is bitten numbly by numb maggots; who walks generously with wide-spread, tentative legs, falls frequently in the gutter, and who sees, in the extremity of his ecstasy, blue mice and pink elephants.

   1913 August, Jack London, John Barleycorn, New York, N.Y.: The Century Co., →OCLC, pages 11–12