Thinking cap - Idioms by The Free Dictionary
https://idioms.thefreedictionary.com/thinking+cap
WEBTo begin thinking or considering very carefully and seriously (about something). If we all put on our thinking caps, 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 on my thinking cap for a minute." See also: cap, on, put, thinking.
DA: 24 PA: 36 MOZ Rank: 100