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

I mean it depends on if they were serious or not.
Either way I’d just try to one up their theories
“You still believe in humans?”
I’d still be friends with them.

Rip the piss out of them & move on.

I would test if they are open to my time travel beliefs. That way we both wouldn’t be hypocrites.

I listen, make an appropriate response, such as “Wow, I had no idea” and move on with the conversation. Occasionally I indulge them but I’m not patient enough to do that for long.

I’d be more surprised if they weren’t goofy.:)
I can keep a good poker face when dealing with crazy individuals but the minute they turn their head… :D

I would talk to them seriously when they were in a more sane mode about my concerns.

I would ask them where they got that idea from as so much is on TV and internet about those types of subjects and if that is where your friend saw it then your friend must be afraid now.

A sane response would be that although the world has not discovered everything that is out in the universe it may be possible and some people make creative stories out of that .

In reality I don’t think that its possible without the world knowing about it?

Your friend was looking for a safe place to confide his/her fears and chose you to confide in.

They are looking for your take on it and hope for a response that would make them feel better and trusting of the world since they don’t trust what they see and hear now.