let something drop
let (something) drop
1. To cease discussing or dwelling upon something. Look, we can't afford a new car right now, so just let the matter drop already!
2. To accidentally or inadvertently reveal some secret or important piece of information. I can't believe your sister let news of our engagement drop in front of your parents last night! The agent, under the influence of a powerful truth serum, let drop the names of other operatives working covertly in the area.
let something drop (or fall)casually reveal a piece of information.
let something ˈdrop
1 do or say nothing more about somebody/something: I’ve heard enough about this subject. Can we let it drop now?
2 mention somebody/something in a conversation, by accident or as if by accident: He let it drop that the Prime Minister was a close friend of his.