gray Idioms 

get/have gray hair

- to have one's hair turn gray from stress

Our teacher is getting gray hair from all the stress.

a gray area

- a question that is not clearly defined and may have a broad or more than one answer, neither black or white

The issue of the tax on children's toys was a gray area for the accountant.

gray matter

- brains, intelligence

I wish that my friend would use his gray matter more effectively when he is making his crazy plans.

Color Idioms

white sale

- the selling of towels or sheets at a reduced price

We went to the white sale at the department store to buy some new sheets.

white-tie event/affair

- an event that requires guests to wear formal dress such as men wearing white bow ties with formal evening dress

I attended a white-tie dinner in honor of the president of our university.

whitewash (something)

- to cover up or gloss over faults/errors/wrongdoing

The government was accused of trying to whitewash the scandal about the illegal money.

with flying colors

- with great or total success

My friend passed the course with flying colors and she now wants to go out and celebrate.

yellow-bellied

- extremely timid, cowardly

The man is yellow-bellied and is never willing to fight for what is right.