many a true word is spoken in jest
The things that one jokes about may in fact be true or become true. I know she said she was joking about being depressed, but I'm concerned—many a true word is spoken in jest. A: "Oh come one, I was only joking! I would never do something like that!" B: "So you say, but many a true word is spoken in jest."
Many a true word is spoken in jest.
and There's many a true word spoken in jest.Prov. Just because something is said as a joke, it can still be true. Fred: Why did you make a joke about my being stingy? Do you really think I'm cheap? Ellen: Of course not, don't be silly. It was just a joke. Fred: But many a true word is spoken in jest.