That slightly surreal moment when you're on your regular commute, and you don't recognise any of the people sat around you.
When you travel on the same train, day after day, you start to recognise the people around you. Regular travellers tend to sit in the same place on the train. It's normally to do with where the exits are on station you get off at. You automatically seat yourself so your positioned for a quick exit before everyone else can gum up the exit.
Today I got on my normal train, at the normal place, sat down and didn't recognise anyone around me. No guy with his bike in the disabled area, no guy with in brown cords and newspaper, no guy with his iPad and earphones. My hardened commuter instinct went into overdrive and I started double-checking that I was on the right train. Next I wondered if I'd overslept and I was somehow an hour late without realising it.
I was on the right train and I wasn't late. I can only put it down to one of those freaky coincidences where all the normal people just weren't there. Perhaps a feeder train or bus was late.
But it did make me think about how much unconscious information you pick up from your environment without even realising it. Until it hits a threshold of course, and then your internal alarm goes off, and your unconscious watchdog shoves it into your conscious mind for actioning. Good job too - I'm glad someone is watching out for me on my commute ... even if it is me :-)