The penny drops

Posted by Lotg (OZ) on September 07, 2004

Remembering something that my mother used to do to me as a child, I was wondering why - and then 'the penny dropped'. But then I also wondered how that saying had come about. My googling produced the answer below:

A realisation after a period of confusion or misunderstanding.
May have originated as a reference to the use of coin (penny) operated slots on the locks or public toilets.

Is this likely? Does anyone have any more info? How can the dropping of the penny in the toilet door equate to the realisation of something? (Oh and btw, the scary thing is that I can remember when we did put a penny in the doors of public and large dept store toilets - yikes!!!)