Exploding Head Syndrome (No Joke!)
Apparently some people wake hear a loud bang in their heads when they wake up. The best part is that it's actually called "Exploding Head Syndrome".
There's an article that mentions it here: http://www.sciam.com/article.cfm?id=...leep-paralysis
Might have happened to me once. I woke up to hear an impossibly loud bang over my dresser which is next to my bed. The sound came from inside my room, didn't sound like a neighbour hitting the wall. And when I checked, nothing had fallen or been knocked over. Was pretty freaky.
http://www.nvnews.net/vbulletin/atta...1&d=1168598094