What is a casual sentence that others take seriously?

That is, if you say something casually, you don't care, and you forget it, but others notice other deep meanings in your words and get unexpected information.

Drucker said:

Even the best boss may say thoughtless things, leading to confusion and wrong guidance. A big company has been using this manager's report for ten years, but the report the boss received contains some goals and standards, which makes him puzzled every time. Whenever he asks, the answer is always: "Don't you remember? This is what you said when you took the elevator downstairs with me last spring. "

: translation:

The speaker has no specific intention when he says something, but the listener will read his own meaning from it.