Slang phrase nigger during the woodpile "a hid motive or unknown aspect affecting a circumstance in an adverse way" [OED 1989] is attested by 1800; Thornton's "American Glossary" (1912) defines it as "A mode of accounting with the disappearance of gasoline," as a result "an unsolved secret.They used samurai swords, shurikens, and other lethal weapo