Idiomatic expression meaning that a secret has been revealed, usually unintentionally, similar to the expression "to spill the beans." Can also be expressed as "the cat is out of the bag."
Bobby let the cat out of the bag when he accidentally mentioned to Amanda the surprise birthday party they were planning on throwing for her.
by VKaizer August 8, 2009
(v.) To accidentaly expose secret information one was privy to, forfeiting the entire "game".
Who let the cat out of the bag to that bitch I was using her for business connections?
by Gumba Gumba May 20, 2004