put thinking cap on

put (one's) thinking cap on

To begin thinking very hard about something, especially a solution to a problem. If we all put our thinking caps on, I'm sure we can come up with a way to earn enough money to go to the baseball game this weekend. A: "Well, boss, what do you think we should do?" B: "Just let me put my thinking cap on for a minute."
See also: cap, on, put, thinking
Farlex Dictionary of Idioms.

put one's thinking cap on

Fig. to start thinking in a serious manner. (Usually used with children.) It's time to put our thinking caps on, children. All right now, let's put on our thinking caps and do some arithmetic.
See also: cap, on, put, thinking
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs.
See also:
  • put (one's) thinking cap on
  • put your thinking cap on
  • put on (one's) thinking cap
  • put on one's thinking cap
  • put on your thinking cap
  • get (one's) thinking cap on
  • keep (one's) mind on (something)
  • keep mind on
  • keep your mind on something
  • blue-sky thinking