I was certain that a gander was a group of geese. Why? Because apparently everybody who has ever used the phrase "what's good for the goose is good for the gander" around me was using it wrong. I just learned this week that a gander is a male goose. So based on misuse, I thought that the phrase meant that what's beneficial for one is beneficial for the greater group, but what it really means is that what's acceptable in the case for one should be equally acceptable for others in the same situation.
I'm nearly 36 and I would say that I'm smarter than most people, but this was a gaping hole in my knowledge that was pretty damn humbling to learn of and correct.
No, it's more like "if Larry gets a 10% grade reduction for turning his paper in a day late to you, then I shouldn't be getting this 20% grade reduction for turning this paper in a day late to you." It's more of a call for things to be fair and give everybody equal treatment.
There was a recent court decision regarding Donald Trump that, more or less, appointing a special counsel for the purposes of DOJ impartiality is not constitutionally acceptable. As a result, Hunter Biden, who was investigated and prosecuted via special counsel in order to maintain impartiality from the DOJ since his father is the sitting president, essentially argued that "what's good for the goose is good for the gander." Meaning that if Donald Trump should have his case dismissed under the pretext of special counsel being an invalid idea, then so too should Hunter Biden. That decision was already generally seen as fucking silly, but the silliness was put on full display for partisan hacks and their audience.