a lesson

If a child shows you their drawing/painting, don't ask what it is or try to guess; just ask them to explain it to you
If you are eating with a friend, offer them your food, since sharing is caring.
If someone tells you a joke and you don't think it's funny, you should still laugh.
When you argue with someone, don't yell as they don't agree with you.
Always call before going to someone else's house to avoid being an "unwanted guest"
Before entering any public transport, please let passengers exit first before entering (requires patience as everyone needs to be somewhere, you are not the only one in a hurry)
If you borrow a car from someone, return it with the gas refilled and in good condition
When you're done shopping, don't leave your cart in the middle of the aisle; park it in the designated area
Don't end an apology with an excuse, it makes the other person think you are justifying your wrongdoing.