I've mentioned before that I sometimes get startled when opening a door when another person happens to be on the other side. 

Thinking about this further (since it just happened again), I'm absolutely amazed that this happens at all, let alone as much as it does, based on the probability of an event like this happening.  Even though I'm a creature of habit, my routine isn't exactly the same from day to day.  Sometimes I walk through a doorway at 9:15am, other times at 9:18am.  The probability of me walking through a specific doorway at a specific time is quite small.  Now multiply that probability by the probability of another person walking through the same specific doorway at the same specific time.  Oh, and they're walking through from the direction opposite me so that I can't see them. 

The chances of this happening are so incredibly small, I'd be amazed if this happened once.  But it didn't happen once.  I would say it happens about once a week on average.  Granted, the doorway I'm talking about is the one to the bathroom, possibly the most heavily trafficked room in the building.  But still, the chances of me encountering a person at the exact moment I open the door and not 2 or 3 seconds before or after is mind boggling. #psychology