100 essential things you didn't know you didn't know is a clever book by John Barrow.
The title immediately caught my attention of course : things I did not know I did not know ? The author is teaching in the Department of Applied Mathematics and Theoretical Physics in the Cambridge University. He has a real talent to describe the world and life as it is through math principles. How does maths can help us understand daily stuff like : how Rugby can help us understand the Theory of Relativity, the 6 degrees of separation between you and anybody else on earth or why does the other queue is always moving faster.
Everybody has experienced that. After having scrutinized all queues in the supermarket, it appears that you've chosen the slowest one, once more !
Simple : just because the slowest lines are the one that have more people in them. In average, just the fact of choosing a line will increase the fact that you have more chances to be in the most crowded line, the slowest one.
Other point to be considered by Barrow, the fact that even though people are amazed by coincidences, there exist far more non-coincidences that nobody looks at...