Question about “Nazi” callsign - just curious

Yesterday we saw a truck with a personalized license plate that said N4ZIM and had what I think were Ham Operator stickers elsewhere on the car.

Is this a valid call sign and are we seeing what we think we’re seeing? Or is there some other significance to this name and we’re reading it wrong?

Seems odd to me that this would be an allowable call sign let alone an allowable personalized license plate.

Like I said, just curious.