chicken-brained
Stupid; narrow-minded; unimaginative.
I can't understand how a bright woman like Helen can date such a chicken-brained guy as Oliver.
get one's brains fried
To sit in the sun and sunbathe for an excessive length of time.
Newcomers to Hawaii should be warned not to sit in the sun too long - they'll get their brains fried.
To get high on drugs.
He can't make a coherent sentence anymore - he's got his brains fried.
harebrained
Thoughtless; foolish.
Most of the harebrained things Ed does may be attributable to his youth and lack of experience.
on the brain
Filling your thoughts; too much thought about; almost always in mind.
Mary Ann has boys on the brain.
Joe's hobby is ham radio and he has radio on the brain most of the time.
pick the brains of
pick the brains about
To get ideas or information about a particular subject by asking an expert.
If you have time, I'd like to pick your brains about home computers.
rack one's brain
To try your best to think; make a great mental effort; especially: to try to remember something you have known.
Напряженное думать; особенно в ситуации когда нужно запомнить то что обязательно надо знать.
Bob racked his brain trying to remember where he left the book.
Susan racked her brain trying to guess whom the valentine came from.
John racked his brain during the test trying to solve the problem.
She was racking her brains for something to say.
Она напрягала мозги, чтобы что-нибудь сказать.