IV Stamped On A Wheat Penny.

Probably someone's initials.

and

As others have said it is a counter stamped coin in the tradition of the ones from the past.
Here are some other common ones

Here is an example of a Masonic counter stamp

And here are some of the pennies I stamp and feed into the money stream in Michigan.

I have since added a another set of stamps. And will start stamping the pennies and put them in circulation.

There is also a one of Kennedy looking at Lincoln


People do it today because they can, The look on a non collector face when they find them,handing them back to the cashier. And even to see if they turn up here.