Merlin Mann, writing on Kung Fu Grippe:
The Two key Rules of the Grocery Store
It's really very simple: 1. if you're in the way, keep moving 2. if you stop moving, get out of the way. This is Ape Law, and we must teach it to our young.
I wish this were required reading. I wish that all people must first pass a test in which they're required to prove that they've memorized these two rules before acquiring their Grocery Store Shopping License™ and being allowed to buy food.