“When you say that the penny dropped, what you mean is that someone has finally begun to understand what it is that you are trying to say.
The individual gets the message.But he doesn’t understand immediately. He only catches on after some time.
“The rookie policeman didn’t realise what was going on, but the penny soon dropped. The two men were trying to rob the bank.” * “Poor Gita didn’t realise that her friends were making fun of her, but finally the penny dropped.”