thinking cap

But his head was too hot to wear a thinking cap, and no story would come at his half-hearted call.

Now you put your thinking cap on and invent a name, something romantic and pretty.

Old Styf answered "yes" at once to their request, and put on his red thinking cap.

There was nothing for it but to bow to the inevitable, break my journey, and put my thinking-cap on.

"And this head of mine would have to put on its thinking-cap," he pursued jovially.