Is there a word for "pretending to joke when you say something serious"?

I'm currently reading "the body keeps the score", and this passage appears in the first page of chapter 6.

(Warning: passage is about emotional trauma, do not read if you're not ready for that)

"I know I wasn't wanted", she told me, "I'm not sure when I first realized that, but I've thought about things that my mother said to me, and the signs were always there. She'd tell me, 'You know, I don't think you belong in this family. I think they gave us the wrong baby'. And she'd say it with a smile on her face. "But of course, people often pretend to joke when they say something serious".

This is a beautiful observation, one of the kind that's worthy of having its own word.

My question for you, is there a word, or phrase that more eloquently captures the idea of "pretending to joke when you say something serious"?

Solution 1:

There is the saying many a true word is spoken in jest. As Cambridge Dictionaries explains, this is

said about humorous remarks that contain serious or true statements.

I've seen this used in two different kinds of situations: The first is similar to that in your quote, where someone is trying to cover up the truth of their (usually insulting) statement by pretending it's a joke. The second is when a truly humorous story or statement also contains some important truth, such as a comedic movie that helps illuminate some part of the human condition that might be too painful to approach in a more serious manner.

The origins of this exact phrasing are murky, but similar sentiments have been expressed by many authors, including Chaucer and Shakespeare (see linked article by The Phrase Finder). It's also sometimes shortened to there's truth in jest, perhaps modeled after the similar English translation of the Latin aphorism in vino veritas (in wine, there is truth/there's truth in wine).

Solution 2:

It's not one word but back in the day, we used to say a person was "crackin' but factin'" meaning that they were cracking a joke but they were really stating a fact.