Red cunt hair

Having put myself through university by working in the construction industry, I can honestly say that I've never heard the words red cunt hair ever used to describe anything other than a red cunt hair.

However, I have often heard the more abbreviated version, cunt hair, used as a synonym for "a little bit". I myself used the term quite often; partly because it was kind of fun to say and partly out of survival. It might sound a little harsh, but you've got to understand that walking around a construction site wearing your school t-shirt and using cutsy, high-falootin' words will only result in you getting a hammer up your ass for your troubles.

Observe:

"It that stud level?"
"Move it a teensy bit to the left and you've got it."
"Whut?"
"I said: A weensy bit more and you've got it."
"Let's try this again, college boy. I asked you if that stud was level."
"Sorry. A cunt hair to the left and that sonofabitch will be right as rain. Hey, did ya catch the game yesterday? Can ya believe those fuckers lost again? Damn, I could use some poontang. You guys wanna a grab a beer after work? Fucking Christ it's hot out here."
"Shut up"
"Okey-dokey."
"Whut?"
"Fuckin-A!"
/me gives the thumbs up and wonders if anyone has ever succesfully killed their foreman with a nailgun.

A very small unit of measurement indeed. When not used in construction as noted above (and, yes, I have used this phrase in a sentence on a construction job-site), frequently used to describe the distance by which one has missed one's intended (or unintended) target.

"I missed tearing my thumbnail off (with a checker-faced framing hammer) by three red cunt hairs!"

Having used this term as a punchline to a joke in the politically incorrect medium of a tattoo parlour, I was surprised at the response of one of the artists, who put down his buzzing tattoo machine and addressed the term at hand.

"You do know that it's an actual measurement in machining?"

Given this bloke's penchant for the leg-pull, I smiled, and the guy tattooing my arm took the opportunity to pause himself and stretch, stiff as he was from holding the unnatural position.

"Back when I was a machinist, a "cunt hair" was 1/64", which if you think about it, is actually thinner than a human hair. But it was typically added to machinist instructions, or the foreman coming by saying "bump it 2 CH" or something on a diagram so that nobody could object to it in writing.

I looked at him quite carefully to see the telltale twinkle in his eye indicating that it was actually a gigantic wind-up, but it never came. Instead, quite the letdown, he brought the tattoo machine back into position and resumed the calf tattoo he was applying.