Okay, I'm in the midst on NaNo brain right now, so stick with me, it will be short and sweet (Because these are words that could be in the NaNo project! ARGH!).
Nano has taken over my head and story. It happens every year, and every year I start yelling in my head, "WHAT are you doing?!" and "Come back here!"
Every year, once things settle down, and I finish the story and start editing, I realize that it's okay, and a lot of great stuff actually came out of the madness. But at the time?
It is seriously like a team of wild horses (probably being egged on by some faeries with waaaaay too much booze in their tiny bodies) has taken the book reins in their mouths and are running with it. We are banking off walls, flying over slow moving pedestrians, it's MADNESS!
This probably doesn't happen to plotters, even during nano, and it really only happens on this scale when I am writing this fast, but wow! Some of my recent writing sessions have felt like I'm hanging on for dear life and trying to get those crazy horses back in control--and am losing horribly.
So what about you, NaNo or not- ever have this feeling? When?
Good luck to us all!