I had a similar experience about a month ago. It was a long dream, so I'll only describe the relevent part of it:

I knew that I was hallucinating, but didn't know that it was because I was dreaming. I first saw flashes of light across my vision and then in the darkness of my room, I could see red lights floating around. I turned on the light in my room (it worked!), and saw what I believed to be an incredible hallucination of the top half of my body sticking out the top of my PC monitor. I reached my right arm out, and the "hallucination" of me mimicked exactly as I did. I started playing around, spinning with my hand out so that it would go through the hand of my hallucination, but as we both spun, our hands collided as though a solid object. We physically held hands. I looked away for a moment, noticing that the door to my room was open, and the hallucination I was holding hands with changed into a woman. Dreams being what they are, this lead me to believe that the hallucination had been the woman standing there all along.