(Thread prompted by the one about seeing someone with lizard eyes, who is possessed by a demon)
I have once. Waken from a dead cold sleep, my girlfriend and future wife said to me "we're not alone". I looked at the foot of the bed and their was a very angry young boy. I was shocked and became afraid myself as I sensed a power there, and then, like a balloon popping, he vanished.
She asked me what I saw, I said a very angry young boy, who looked to be age 9-10. She confirmed that was what she saw too.
I suppose it could have been an angry guardian angel, or even a passing demon, but let's go with ghost.
I have never doubted things spiritual since that day. I was about age 19.
Middle of the night dark, but some ambient light from moon, and electronics in the room, etc. I remember a faint yellow light that seemed to emanate from the ghost, but I can't be sure.
I see. So is it possible there were just some shadows and things that looked like a boy in the dark? Until there was a change to the electronic light, trees casting shadows moved or you and your girlfriend moving?
The materialist in me would say this, but the key things that changed my mind was that she woke me up saying "we're not alone" but nothing else. I looked and saw what I saw, and then she asked me what she saw, and I said the angry boy. Then she confirmed that she saw this as well. Also, inexplicably the lighting didn't change and what we both saw disappeared.
There is no such thing as a shared hallucination.
I'm not suggesting it was a hallucination but that you could have both seen an illusion created by the light and shadows. If the light didn't change then perhaps it disappeared as your eyes adjusted. There are optical illusions where you can see a person one second then see a different figure and lose the person and have difficulty seeing it the first way again. Or it could have been a ghost for all I know.
All I can say is I saw what I saw when I saw it (if you catch the movie reference).