I looked in my mind for something appallingly stupid to say, with the object of distressing and teasing Mrs.Fyne.

It is humiliating to confess a failure.

One would think that a man of average intelligence could command stupidity at will.

But it isn't so.

I suppose it's a special gift or else the difficulty consists in being relevant.
Discovering that I could find no really telling stupidity, I turned to the next best thing; a platitude.