I worked at Zellers for two years as a cashier (2004-2006), I constantly got yelled at by customers for doing my "HI5's" as they called them, and even had a lady throw her merchandise in my face!
We had an awesome manager at the time who made me a receipt paper sign with a middle finger saying, "Fuck you its my job."
Then one day he got transferred and Bitch From Hell came in. She would stand over our shoulders with a clip board and make sure we asked every customer. Oh and get this, if we didn't ask because we saw the cards in hand that they were going to use, we still got in shit.
I finally told her she was a frigid bitch who could kiss my ass and to stop taking her anger out on me because she was a sixty year old with no future and promptly quit. :)