Slang phrase nigger inside the woodpile "a concealed motive or unfamiliar issue impacting a predicament within an adverse way" [OED 1989] is attested by 1800; Thornton's "American Glossary" (1912) defines it as "A manner of accounting with the disappearance of gasoline," as a result "an unsolved secret.The slang phrase "Niga" is a hugely offensive