Serious question HN: I often see parents have an almost instinctual need to feed their children bad information and see if the can detect the falsehoods.
I do this with other people who aren't kids, though I try to keep it to family and close friends so that I don't thrash my reputation too much. Typically I'll pick a theme (say, "citrus fruit, and related topics") for a particular family get-together and see how many semi-plausible but invented facts revolving around that theme I can inject into conversations. Sometimes I'm rewarded by hearing facts that I made up regurgitated years later (one that I am proud of is that orange juice turns an opaque white when pasteurized, and needs to be dyed back to orange (like margarine) for sale.)
Fundamentally I think this is an exercise in creativity; sort of like telling a good campfire story of your own creation. So far as people play this game with kids, I suspect it is because kids are easier to fool so the game is more rewarding.
I do this to my son because small children (<3) are such amazing mimics that it's hard to tell if they truly understand a concept without testing positive and negative responses.
I could make my 2.5yo kid seem like a genius to strangers by asking the right questions. As a trivial example, I know he usually says "yes" when asked a question he doesn't really understand.
There are better ways of teaching children that people lie, and that information is not always accurate.
Besides, people don't always know that they're passing on bad information, so you'd have the situation where someone is passing on stuff that is wrong but saying "no! this isn't part of the game! this stuff is really real!"
Is this instrumental in teaching "savvy" ?