Entitlement: "Not should someone pick up my shit, but in special circumstances, on a busy day when the established system doesn't work, someone else should still pick up my shit."
How often do we stop and think about how pampered our lives are, that our trash is magically whisked away to a landfill we never have to think about. That's nice, just by itself. Go camping in the wilderness where you're expected to haul your own trash back home with you in your car... really makes you think about it.
Overflowing trash cans became my pet peeve, forever. Is the trash full? Then take it out. If you can't, then go find another one! Setting your trash next to the trash can is the worst thing you can do. You're a real asshole if you think that's okay. It sends a message that you think someone failed you, they weren't there to take the trash out fast enough so they deserve to be punished. Their punishment is more important than you taking a few more steps to find another place.
The next year at college I was the RA so I was in charge of the floor. I removed all trash cans from the bathroom and hid them for the first three days. It forced people to ask where trash belonged. I told them about the dumpsters outside.