nigger in the woodpile

Etymology
First attested in the 1840s.

Noun

 * 1)  A hidden motive, influence or factor; a concealed (potential) snag; something suspicious.

Translations

 * Chinese:
 * Mandarin:
 * Finnish: olla koira haudattuna, jotain mätää
 * French: anguille sous roche,
 * German:
 * Russian:
 * Spanish: gato encerrado