A blue hair American noun phrase
The noun phrase "a candy cotton hair (hairstyle)" can be replaced by the one "a blue hair" with the meaning that refers to a dyed-blue hair.
Used to imply a woman who is old
Those blue-hairs are so talkative that I can't hide anything away from them.
Used to describe a dyed-blue hair
Look, Tommy. I've just got a blue hair. What do you think?
To ask someone something in a very straight, direct way, sometimes even a rude way
A blue hair seems to be fit your face better.
I'm afraid of getting old because I might have got a disgusting blue hair.
This term was used first in the US in the 1940s. A parallel term popped up in the UK in the 1950s: “the blue-rinse brigade.” This term specifically referred to elderly women whose out-of-date hairstyles were thought to reflect out-of-touch, conservative values.