I've worked retail for about 4 years (and will probably do so until I find a job in my actual field), but let me tell you, there are equally as many stories from the worker's perspective. Belligerent (or just plain insane) customers, Freudian slips of the tongue, and an 80 year old woman in a walker shoplifting the new DVD release of Gone With the Wind.
There was a guy at my store (a bookstore) who was so angry we didn't have the book he was looking for, he began bashing his head, at full force, against the customer service desk.
Another story is when I was cashiering, and I normally joke around and laugh a lot with people. This was my Freudian slip: I was ringing up a rather large woman, and she gave me the money, then fished out some coins so she'd only get full bills for change. She said something like, "I like to get rid of my change.", and I said (something I say often when people do this!): "Less to weigh you down, say?" and my palm mentally faceplanted me. It was then I learned that retail punchlines are truly situational. Luckily, I think it went over her head.
Oh! And let's not forget the creepy stalker guy who came on to me... helped him find a book, and then ordered him one we didn't have. We were casually chatting while doing so (again, something I often do), and he asked what I study. I told him, Chemistry. Then, in a line that has become legendary at the store, he said, "What's a chemical equation for my heart racing while looking at you?" He then pointed to the monitor and said, "Keep my number. Call me."
It was the only time in my life that I was literally speechless.
