What would you do if a good friend of yours suddenly shows a very unsuspected ('crazy') side of then?

You’ve known them for a good while, you share several interests and opinions/views, but then, out of the blue, they state that certain politicians are not human, but alien.
And that it is obvious because sometimes you can see that their eyes turn black.
And there’s proof to be found of the latter online.

Although this sounds funny, and ludicrous, and can be answered with a similarly funny remark, I would like to hear how you would deal with such scenario after serious thought.

But please, if you will, humor is appreciated as well.