Here are some unwritten rules from experts on how to behave in parking lots, airplanes, stores, etc.:

Navigating a crowded sidewalk. Walk on the right and pass on the left. And don't walk with more than two people side by side, blocking the whole sidewalk!

Sitting next to a chatterbox on a flight. Start with nonverbal cues -- open a book or put on headphones. If that doesn't work, politely tell them you don't want to chat.

Claiming a parking spot. Never let a passenger hold a spot by standing in it. It's OK to follow someone from a store to their car -- just ask, "Are you leaving?"

Shopping cart blockage. If someone's cart is blocking the aisle with only groceries in it, feel free to move it. If the shopper has left a purse or baby in the cart, hands off!

Umbrella etiquette. On a rainy day, when everyone's carrying an umbrella, tall people should always raise their umbrellas to let the shorter people get by.

Reading over someone's shoulder. Careful you don't lean into someone's personal space. Reading the back of someone's paper is cool -- asking them to turn the page isn't!

All this stuff reminded me of one of my favorite cartoons in Highlights Magazine for kids--usually seen at the Doctor or Dentist's office. Remember "Goofus And Gallant?"