put your 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 your thinking cap on

or

get your thinking cap on

If you put your thinking cap on or get your thinking cap on, you try hard to solve a problem by thinking about it. We need to put our thinking caps on and decide what can be done to prevent the problem. We've got five pairs of boots to give away, so get your thinking caps on and answer the following questions. Note: This expression may refer to the cap which judges used to wear when passing sentence or judgment.
See also: cap, on, put, thinking
Collins COBUILD Idioms Dictionary, 3rd ed.

put your ˈthinking cap on

(informal) try to solve a problem by thinking hard about it: Now, how are we going to find this money? Let’s put our thinking caps on.
See also: cap, on, put, thinking
Farlex Partner Idioms Dictionary
See also:
  • put (one's) thinking cap on
  • put 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