Two shop workers commenting on the big green guy working at the lathe. . .

"I've been wondering about him ever since I saw him using a frog hair for a feeler gauge."

A "frog hair" is a machinist's term for a very small amount (usually thousanths of an inch or less) from a more genteel era. Today the terms used cannot be used in polite society or this public web page.

"Frog hair" adjustments are almost impossible movements of work that once moving usually moves much farther. Nudging heavy work with a soft hammer sometimes works but overtravel is common. Then other colorful language is used.