I had a dream once where I was exploring this creepy abandoned house (in the daytime mind you), at some point I said I forgot something and turned around to go back down this hallway. I guess I must've been making some noise IRL because my girlfriend at the time decided to wake me up by shaking me. Back to me in dreamland, I'm walking back down this hallway when suddenly my girlfriend jumps out of a closet! I'm awake now, and my girlfriend is right in my face, right where she'd appeared in my dream, so I began screaming in her face, which in turn made her scream in my face. That's the only time I've legit screamed out of fear.