I don't have any good pregnancy brain stories yet from this time around, but when I was pregnant with dd, I had a doozy.
We were all out on a walk. When we came back, I was tired, so I just wanted to sit on the couch and continue reading the book I had been reading before we left. I looked on the arm of the couch, where I was sure I had left it. No book. I looked on the couch, on the floor, under the couch, everywhere. No book. I finally decided to just sit and do something else, but it was really bugging me that I couldn't find this book. Where could it possibly have gotten to??
So, I was sitting on the couch, doing something else, but every couple of minutes I stopped and thought, "Where could that book be?" I was really annoyed. Finally I decided I just couldn't concentrate, so I would just get up and search for the book some more. In order to do this, I put down the thing I had been holding and using as my alternative activity. When I put it down on the couch, I finally processed what that alternative activity had been.
I had been reading my book. My *missing* book.
I apparently came in the room and picked up the book automatically, without thinking about it at all. Then, when I looked for it, it wasn't on the couch, because it was in my hand. I held it the whole time I was looking for it. Since I was holding it, when I decided to give up on looking for it and find something else to do, it was just natural to start reading it. And then I read it for 10 minutes or so, pausing periodically to wonder where the heck it was.
It was definitely one of the weirdest experiences I've ever had.