Skeleton in the closet or Skeleton in the cupboard is a colloquial phrase and idiom
used to describe an undisclosed fact about someone which,if revealed,
would have a negative impact on perceptions of the person."Cupboard" is
used in British English instead of the US English word "closet".It is
known to have been used as a phrase,at least as early as November 1816,
in the monthly British journal The Eclectic Review,page 468.