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general::
Phrase(s): know shit from Shinola [and] tell shit from Shinola
Fig. Inf. to know what’s what; to be intelligent and aware. (Always in the negative. Shinola is a brand of shoe polish. A person who doesn’t know shit from Shinola is very stupid.) • Poor Tom doesn’t know shit from Shinola. • Fred can’t tell shit from Shinola, and he’s been made my boss.
McGrawhill's American Idioms And Phrasal Verbs