Common courtesy

Or, how not to be a total asshole to complete strangers. Please expand.

1. Entering or exiting a building: look behind you to see whether anyone else is coming through the same door in the next 5 seconds. If the door will slam in the face of the person behind you, hold it open.
2. If you see someone right outside, and opening the door would involve no more effort than extending your arm, go ahead and give it a push.
   • In particular, let the pizza dude inside, even if it ain't your pizza. We're lucky to get delivery here.
3. If you see someone carrying boxes, ask if there's a door you can open.
4. If someone is standing in front of a dorm with a sleeping bag and a prospectus, and appears to be under the age of 20, offer to swipe the person in.
5. If you cook in a kitchen, for God's sake, clean up after yourself. Don't leave your spaghetti sauce on the stove top until spring break. If you cook and "that mess was there when I got here," just take a few minutes and clean it up anyway. Your guests probably don't want to eat in filth.
6. If there's only one omelet left at the dining hall, ask the person behind you if they want half.
7. Don't throw your old sardines, or any other stinky refuse, into the bathroom trash can. There is a trash room.
8. Knock the lint out of the lint screen after you use the dryer.
9. Talk to your janitor.
10. If possible, leave space on the sidewalk so others don't have to walk in water, mud, or snow. If you're walking in a group and one person comes in the opposite direction, move behind someone in your group so the person passing can use the sidewalk as well.
11. If the room is empty, and you're leaving, turn off the lights. Please.
12. Take off your hat indoors.
    • Find a way not to be offended by those JERKS who would dare wear HATS indoors. How dare they though, right? Outrageous.
13. Say hello to people you meet. If someone else says hello to you, respond in kind. Bonus points for smiling while saying hello.
14. Don't destroy or abuse property. Particularly not if it belongs to somebody else.
15. Say "excuse me" rather than just pushing past people in a crowd or a constricted space.
16. When in class or in the library, put your cell phone on vibrate. PLEASE.
17. If you yak or see someone yak in a place that's a bit out of the way--a basement, far-off corner, or anywhere that isn't a toilet, really--make your best effort to tell someone responsible that there's a stinky, biohazardous mess on the floor.