Everyone knows the well known phrase, staring into space. How couldn't you. You see, I'm thinking about the hundreds of times I've done it and not realised.
For instance, I was at the dinner table a couple of nights ago and I randomly started glaring at my sisters plate of food( she was sitting opposite me)...staring into space. I honestly have no idea what I was thinking about, just that I was there for a long time.
I only realised that I was doing when my sister said " What is it on my plate that your so interested in?!" waving her hand infront of my face... I still laugh at it now.