What is the origin of the idiom "pink elephants" and when to use it?

The origin of the idiom "pink elephants" in the context of hallucinations or alcohol-induced visions can be traced back to the early 20th century. The term became more widely known and referenced through various forms of popular culture, such as literature, films, and cartoons. One notable example is the 1941 Disney film "Dumbo," where the main character, Dumbo the elephant, experiences a sequence featuring pink elephants after accidentally consuming alcohol. It is often used in social gatherings, parties, or casual conversations when discussing the effects of drinking or referencing the idea of seeing things that are not there.