If you have something, it will be easy to prove your possestion. It is enough to show that, then every body will accept that you have it.
If you do not have something, it will be logically impossible to prove. Because whatever you do, they might think that you are hiding it.
When someone insists on such an irrational argument, it means that he wants something else which is provable. What it is , I do not know. I can only hope that it will not cost me a lot.