Sayings

1. Blue
Out of the blue: unexpected
True blue: to be loyal or faithful
Once in a blue moon: an event that occurs infrequently
Feeling blue: to feel sad or unhappy

2. Green
Get the green light: get approval to move ahead or proceed with a project or task
Green corn: the young, tender ears of Indian corn
Turn green: to look pale and ill as if you are going to vomit
Going green: when someone or something makes changes to help protect the environment, or reduces waste or pollution

3. Yellow

Yellowbellied: a cowardly manner

Yellow fever: a disease involving high fever and jaundice that is common in the tropics

Yellow jack: a flag flown on a vessel to show that it is under quarantine

Yellow journalism: newspaper articles thought to be sensationalized in order to sell more papers 

4. Red

Red in the face: to become embarrasse

Seeing red: to be angered

Red flag: a warning of danger

Not worth a red cent: having no value

5. Pink

Tickled pink: to be happy

In the pink: in good health

Pinkie finger: the smallest finger on the human hand

Pink collar: refers to a particular class of jobs once only filled by women