In English, we say a bad penny always turns up.  Today we use it to refer to a person we’d rather not see but who keeps coming around anyway.  We don’t think of it as referring to a literal bad penny, a counterfeit penny.  Really, how many of us have ever seen a counterfeit penny?  I’ve been collecting coins for most of my life and I haven’t run across one, or even heard of anyone counterfeiting them.  Why bother?  They wouldn’t be worth the effort you put into making them.  If you’re going to counterfeit, go for $20 bills, or even quarters, at least. There was a time when pennies were worth a bit more, and were worth the effort to counterfeit.  In 15th century England.  At this time, the English penny was a silver coin, not copper.  (There were coins called farthings which were smaller than pennies, and these were made of copper.)  The penny was a fairly valuable coin—more valuable than we think of pennies today, anyway.  It makes a kind of sense, then, that people would counter