Does not know come here from sic them

Does not know "come here" from "sic' them" is an idiom to denote complete ignorance. The person or thing that is being discussed is being compared to a dog that does confuses the command to "come here" with the command to "sic them" (that is to attack). When spoken with a thick Texas accent, the phrase rolls of the tongue as "don't know comer from sikum." It has also been shorted to "Here from sic 'im".