How Do I Make This Hard to Misuse?

That aspect of 'cp' always drove me nuts, probably because I learned MS-DOS first.  I've found
myself tempted to write a wrapper around 'cp' to make that form work.

I won't, though, only because I know it'll wreak havoc when I go to use someone else's account
for whatever reason.  (e.g. to show them how to do something.)