Colour Idioms:
1. Chase Rainbows.
Def: To try to get or achieve something that is difficult or impossible.
Origin: The term comes from the old tale about finding a crock of gold if one digs at the end of the rainbow, where it touches earth.
There is a popular song “I’m Always Chasing Rainbows” with words by McCarthy and music by Harry Carroll, this song was published in 1918. Also this idiom used in several films, for example in Ziegfield Girl.
Example: My friend is always chasing rainbows and he never achieves anything.
2. Carte blanche
Def: Permission to do something in any way you choose to do.
Origin: From the French it means “white(blank) paper” – the military term for surrender. This expression started to become popular in the 1700s then King Charles II offered a “Carte Blanche” to anybody who would help him escape. This was a 'blank sheet' with his royal signature at the bottom, meaning that the recipient could write anything above the signature and it would be legal.
Example: Currently, drug makers have carte blanche to set their list prices.
3. See pink elephants
Def: To see things which are not really there because they are only in your imagination.
Origin: The phrase became especially popularized by the 1941 Disney animated film Dumbo, in which the title character accidentally becomes drunk and sees a parade of pink elephant hallucinations.
Example: John was seeing pink elephants according to those who listened to his story
4. Born in the purple