I'm looking for a word/phrase which means "spoken comically at the time, but in retrospect, is appropriate/fitting to the true nature of the speaker."
If the word also has the added connotation of making the speaker unintentionally funny/buffoonish for these hidden/hypocritical that make his comic statement apropos, that'd be great.
The closest example I can think of would be a public figure who makes a joke about a topic that (s)he doesn't really believe in, and then it's later found out that they seriously believe it. IE, if a liberal politician said a joke about how a woman's place should be in the kitchen and it was taken lightheartedly (as if that's possible), but said politician was later found to be deeply misogynist, shedding light on the joke as indicative of his true belief.
Another example, self-deprecating humor that turns out to be true and a serious issue.