Why do we say we have "a pea in the head"
The expression having “a pea or a chickpea in the head” is quite simply the image of a small brain, synonymous with a lack of intelligence. This expression therefore means to be completely stupid, stupid, not smart.
We don't just use the pea to imply that someone is stupid. There is also the flat pumpkin seed or the chickpea (the variant "to have a chickpea in the head" which has the exact same meaning).
In Pagnol, for example, in Fanny:
“…his brain was drying out. Escartefigue, stupefied! Panisse, lugubrious. This poor brain, little by little, it has become like a chickpea. And then, dear, when he walked down the street, that little brain popped into his big head and it sounded like a bicycle bell. »
Already in the Middle Ages the pea was associated with madness. “to have peas and bacon” meant to be treated like a madman.
