know shit from Shinola

Etymology
A colloquialism which dates back to the early 1940s in the United States, sometimes ended with "that's why your shoes don't shine". Shinola was a popular brand of shoe polish.

Verb

 * 1)  To have the most basic level of intelligence or common sense.
 * 2) * 30 October 1973, George Carlin, "Filthy Words", WBAI Radio, quoted in FCC Reports, Second Series, Volume 56, October 31, 1975 to January 16, 1976, page 101:
 * "He don't know shit from Shinola. (laughter) you know that? Always wondered how the Shinola people felt about that (laughter) Hi, I'm the new man from Shinola. (laughter) Hi, how are ya? Nice to see ya? (laughter) How are ya? (laughter)"

Usage notes

 * Almost always used in negative constructions to describe someone's ignorance or stupidity, such as: He doesn't know shit from Shinola.

Synonyms

 * know one's ass from a hole in the ground