I had this dream a couple months ago:
My girlfriend and I were driving to the rock gym and I thought I would play a mental game with her. I started asking her how she knew she wasn’t in a dream or coma. She couldn’t answer the question. I then asked her how she knew that I wasn’t her subconscious trying to wake her up in the real world. I said "Wake up Mona, its time to wake up". She had a freaked out look on her face like I was really getting to her, so I continued with a sterner voice, "Mona, we need you back home, you need to wake up." I sat back in my seat feeling quite satisfied that I had sufficiently succeeded in cracking her fragile psyche when I began to ponder the same question myself. After a little thinking, I came to the conclusion that I couldn’t be in a dream because everything felt too real. Then I woke up.