I worked for a crappy department store that is hell on earth for two holiday seasons and I honestly hope I never ever am subjected to that awfulness ever again. Customers were always a bit terrible but around the holidays they somehow became worse, I think it's because they felt entitled to everything.
One year I worked a shift from 6 am to around 12, in the shoe department, and the whole time I pretty much didn't move away from the cash register. Except for when one women basically had a meltdown because the shoes that she wanted were "listed" incorrectly and therefore I ought to give her a discount on them.
She threw a fit all while a line of at least thirty people stood behind her. One of the managers made me give her the discount even though the lady was completely wrong. That was horrible and made me feel like a complete idiot.
One of the reasons why I strongly dislike retail is the way people treat you; as if you are nothing and as if you are as dumb as rocks (this is from the customers and from the bosses). This story isn't even the worst of it though to be honest I think I may have blocked some of the true horror stories from my memory they were that awful.
I also would say "happy holidays" to people since I didn't want to assume their religion (and from my own experiences as a jewish women) and I got bitched out a few times for not saying "merry christmas" by customers. That was always fun, not. So my heart goes out to anyone working Black Friday and the holiday season in general, it's an unpleasant time of year.