Slang phrase nigger in the woodpile "a hid motive or unknown aspect affecting a scenario in 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," hence "an unsolved mystery.They utilised samurai swords, shurikens, along with other deadly weapo