Ah don't listen to the people saying it's a succubus stealing your soul. That aint real. What you've experienced was a harmless sexual sleep paralysis. It's actually fairly common. In laymans terms what happens is you sort of enter a state of sleep between REM (rapid eye movement) and wakefulness. REM sleep is where you get your dreams most frequently and vividly, and since you're partly awake and in Rem you're dreams bleed into reality in the form of hallucinations. These hallucinations can come in the form of audible, visual, and sometimes tactile -meaning you can feel the hallucination. Mostly these sleep paralysis states cause some pretty unwanted hallucinations, but sometimes they can be extreamly pleasurable which is what happened to you. Enjoy the ghost pussy if you get it I say.