I worked for a grocery store as a cashier during a semester of college...
One day, we got a warning about people going around trying to short-change cashiers by asking to break and combine things rapidly in hopes of getting more money than they'd handed over.
Somebody tried it on me, but I happen to be really good at computation in my head, so I had no problem with it...and when it became apparent what he was doing, I ended up shorting him some money. :P
I gave people food packages and signed people in at a soup kitchen for mandatory community service. There would be people arguing about what they wanted taken out or more of in their food packages. And the people who had to sign in, well, I don't really remember it too well. Except some people would yell about something? I don't remember what they were unhappy about X'D.
I live in a place where talking to cashiers is sort of scary. People don't really talk with each other here as the norm, I think. Mutual awkwardness for most ^^;;