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.
Words nearby put on one's thinking cap
put on a pedestal,
put on airs,
put on an act,
put on hold,
put on ice,
put on one's thinking cap,
put on the dog,
put on the feed bag,
put on the map,
put on the spot,
put on to