Upon leaving my body I floated around my room. As many times when i have projected I have encountered entities that mimicked close friends and or people I am generally around. This OOBE ( or lucid dream, which ever is unclear to me) was like the others for the most part, that being two entities which took the form of people I knew watched me. Backtracking slightly, in a prior lucid dream I decided to see what would happen if I yelled. The result was the shaking of the dream location around me. It began to crumble before I awoke. I wanted to test this again and see what would happen perhaps if i stayed for a prolonged period of time. As i yelled or rather screamed I felt would vomit. Soon after that feeling I collapsed and saw red blood apparently I coughed up. Upon awakening my throat was in pain for quite some time. the desired effect was still the same, I shook the entire area.
I more than likely wont attempt it again, much better things for me to explore.
Still slightly interesting to myself, i felt I would share. :-)
I've seen people or whatever while I was OOB take on the form of people that I'm familiar with as well. I always think they're trying to trick me, LOL. I think I've read somewhere before that one can encounter those who are dreaming or unconsciously OOB (and obviously those that are consciously projecting).
I've never tried yelling in a Lucid Dream before but it sounds like you had an interesting experience by doing so.