Be green with envy

To be green with envy is to be unhappy because you wish you had something that someone else has.

• Margaret will be green with envy when she sees your new car.

Have green fingers

When you have green fingers, you are good at growing plants.

• Alice has green fingers. Look at her garden.

Once in a blue moon

If something happens once in a blue moon, it happens very rarely.

• I visit them once in a blue moon.

Scream blue murder

To scream blue murder is to shout very loudly because you are in great pain or you are very angry.

• The little girl screamed blue murder while the doctor tried to give her an injection.

Talk a blue streak

To talk a blue streak is to talk a lot without pausing.

• The boy didn’t talk until he was five and then he started talking a blue streak.

Turn the air blue

To turn the air blue is to use a lot of swear words because you are angry.

• When he discovered that he had been cheated he turned the air blue.

Until/till you are blue in the face

This informal expression is used to suggest that there is no point in doing something because you will not succeed.

Shrinking violet

A shrinking violet is a very shy person.