> My psychiatrist once asked me if I'd seen anything that didn't exist. My immediate question in response is how would I know.

I can't believe you have never experienced thinking you saw something, then looking back and realizing you couldn't have. EG in my case, my cat who has been dead for over 5 years, and the other one of a different colour who has been dead longer than that. By definition a hallucination is something you know isn't real. If you don't know it, you are psychotic/dissociating. So, if you did hallucinate, that's a good thing. EG if the walls are waving and worms are coming out of them, as happens to someone I know, ideally, yes, you know it can't be true and your mind overcomes your strong perceptions. Hardly a laughing matter in that case, but it can sound funny to those of us who haven't experienced it.

Oh, here's another one - hearing voices calling your name because you took codeine for pain. I've had that. I did not know what was going on. Scary, but once you know to predict it, you can know it is not real.