PROVE IT.
It should be a basic Human Right that everybody, everywhere, should have the right to demand that anybody who makes any claim should be required to PROVE IT when asked, or otherwise to retract the claim.
In democracies with strong freedom-of-speech rights, we already have that right. We can "demand" that people prove it, but they also have free-speech rights, so they can chose not to prove it if they want. Then we have the right to take what they say with a grain of salt.
