I was in a large room, trying to figure out something with an associate. There was a puzzle to solve, and/or a crisis of some sort, and we were trying to determine what was coming next. I glanced up at the ceiling way above us, and I saw a swarm of snakes. The ceiling was absolutely covered in snakes, and as I watched they all started swarming in the same direction, to a hole of some sort in one corner.
I thought it could be a crucial key to our search. "Hey," I said urgently. "Hey, look up!" My associate did not respond, so I said with even more urgency, "Hey! Look up there!"
"What? Look where? What's up there?" The voice came from next to me. The pictures blurred and vanished, my head felt fuzzy, and I realized I was in bed. Oops.
"Nothing, sorry, it's okay, never mind, just a dream. Go back to sleep." I was still disoriented, but realized that it had only been a dream. Apparently I'd been so caught up in it that I'd spoken aloud in real life.
My sleeping companion, who I had rudely awoken, got up to use the bathroom. Upon return, he pulled me close. "What was that all about?"
"Snakes on the ceiling," I explained.
"Oh. I was having a really weird dream too." He proceeded to describe it in elaborate detail, while I fell back asleep. Fortunately, if there were more snakes I don't remember them.