a skeleton in the closet
skeleton in the/(one's) closet
An embarrassing or shameful secret. Primarily heard in US. If you've got a skeleton in the closet, it will probably be exposed during this campaign. He didn't believe me when I said that I didn't have any skeletons in my closet.
a skeleton in the closetBRITISH, AMERICAN or
a skeleton in the cupboardBRITISH
COMMON If someone has a skeleton in the closet or a skeleton in the cupboard, they have a secret that would cause great embarrassment or shame if other people knew about it. But everybody's got vices, haven't they? There's always a skeleton in the closet somewhere. Note: This expression is variable. Show me somebody with no skeletons in their cupboard, and I'll show you a skilful liar.