i think this would probably explain the phrase "silly goose"
I imagine the whole point is to say that someone is "sillier than a goose" famously known for, not being silly at all. Arguing that you are so silly, that you look like a goose being silly.
This is why you have to run when you find a goose among your ducks.
I thought up Goose as a superhero for a street level setting, essentially she's a tough scrapper, easy to underestimate, and is really good at blending into crowds or workstaff. Mistique without the mutant shapechangey stuff.
I actually might be able to provide some insight to this. My wife is Balkan and the first time I called her a "Silly Goose" she became madly upset. It turns out in her language the phrase "Glupova Gusko" (Stupid Goose) is a common insult. It is considered incredibly harsh in her culture. My guess is that the phrase "Silly Goose" is borrowed from a Slavic Language and lost its harshness when it moved into English.
It’s a common insult in many languages - with a lot of theories about origins.
You can track medival usage of this all over Europe, but I have no knowledge about other continents.
Insults in general hold more power in honor-cultures. Your grandparents might have reacted the same way she did, while you might not feel the same.
I know of at lest Nordic languages, german languages, slavic languages, Urdu, Yiddish
Some are not literal translations, but have the same meening. Like silly as a goose - not stupid. Or just beeing refered to as a goose implying simplicity, stupidity or sillyness.
The silliest person I know was deadly serious and no-nonsense at work. Their silly side only came out among friends. Maybe you just need to befriend a goose?
Believe it or not, I am actually really serious at work, unless we are friends. I have to be super accurate all the time and I hold myself to very high standards.
I asked my goose friend what he thinks about this and he just honked. Though I suspect he didn't hear me, since he seemed to be busy balancing on his unicycle (his feet can't reach the pedals, so he has to flap his wings to balance)