tradesman:take a fly shit of that shaft apprentist: (blank look) tradesman:thats 1 thou dickhead apprentist: (blank look) tradesman: oh thats right
a very small amount that needs to be taken of something  eg machining a shaft ,scraping a white metal bearing
"tradesman:take a fly shit of that shaft apprentist: (blank look) tradesman:thats 1 thou dickhead apprentist: (blank look) tradesman: oh thats right" What is the definition of "fly shit"?