idioms

  a bad apple (a dishonest or immoral person in a group who does bad things that affect others) They are not going to tolerate a bad apple in the organization. If you want to deal with bad apples, take them out of the group as quickly as possible.   …

  be the brains behind (someone who provides ideas and plans for an activity) Someone very clever must be the brains behind such an organized bank robbery. He was the brains behind the all operations. be the brains behind – English Vocabulary  

  beat your brains out (think very hard about how to deal with a problem) I’ve been beating my brains out all week trying to find a solution. We have to beat our brains out to finish project on time. beat your brains out – English Vocabulary

  beat someone’s brains out (hurt someone badly) If you come back again, I’ll beat your brains out. He fell from the cliff and beat his brains out. beat someone’s brains out – English Vocabulary

  all brawn and no brains (to be physically strong but not intelligent) John is a good football player, but he is all brawn and no brain. He has a good body, but he is the brawn, not the brains. all brawn and no brains – English Vocabulary