Guess
This is a very sarcastic measuring tape. If he bought it at a prank store then we get it and it’s a pretty funny joke. But if this was a mistake and the hardware store sold him a tape measure without measurements, we really do not know what to say.
We didn’t even know that those were a thing, why would that even exist in the first place unless it was a defect from the factory it came from? That must be it because nobody can use it except for pretending it’s a sword and fighting with friends. Don’t act like you never did that as a child.