Birdbrain.

Birdbrain ( możecie też spotkać się z pisownią bird brain)  - a stupid or silly person, czyli po angielsku,tak jak po polsku, ptasi móżdżek, symbol głupoty.  Jeśli ktoś was obdarzy takim epitetem, nie obrażajcie się. W świetle najnowszych badań nazwanie kogoś ptasim móżdżkiem można uznać za komplement.
https://www.youtube.com/watch?v=vYcRiqNoZ0s
A new study has found that bird brains have significantly more neurons than do mammal – even primate – brains of the same mass.
Birds consistently have more neurons packed into their small brains than are stuffed into mammalian or even primate brains of the same mass. That’s according to a study published June 13, 2016 in the Proceedings of the National Academy of Sciences that systematically measured the number of neurons in the brains of more than two dozen species of birds, ranging in size from the tiny zebra finch to the six-foot-tall emu.
http://earthsky.org/earth/its-not-an-insult-to-be-called-a-bird-brain