put on (one's) thinking cap(redirected from put on his thinking cap)
put on (one's) thinking cap
To 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."
put on one's thinking cap
Think or reflect seriously, as in A new slogan? I'll have to put on my thinking cap for that. This term originated in the late 1800s and replaced considering cap, which dates from the early 1600s.