I have a weird 1986 D penny. On the front it looks as if there is a background semi circular indent on the left side. And on the back in United States of America the end of States and of are what seems to be smudged. As in smudged by a finger during minting? I don't know I'm very intrigued though!
You can’t “smudge” the lettering in the minting process.. it a greased filled die vary minor... happens all the time.. common..
Hahah I was entirely unaware there was a term for it but I find it quite comical a name and therefore enjoy it.
As stated above on the reverse. The obverse is a result of a worn die strike. http://www.error-ref.com/design-devouring-die-wear/
It’s an item I would go ahead and put it into a 2x2 and note the “error” and save it to refer back to later as you learn... edit: it’s not a error by the way..
To be fair, that coin is in great condition for its age! It's pretty hard to find older Zincolns that haven't toned a muddy brown over the years.
When debris/grease are deposited in the depressed areas of the die over time, the resulting image after the planchet (coin) is struck by that "grease filled" die (as more senior members have already stated above), looks weak or can even disappear completely! There are many "In God We rust" coins because it happened to the "T." Here's my 1921 cent with lots of grease filled fun. I keep it and call it my "192 BERTY E-CENT."