Worked (for a whole two months!) at a well known chain of pharmacy/convenience stores when I lived on the east coast.
- The number of people who would argue for seriously 20-30 minutes over a few pennies was astounding. Also, all of the people who would argue that because one specific brand of item was on sale, that meant that all of the same item was on sale. (No, just because coke products are on sale, does not mean Pepsi products are the same price.)
- People would do some gross, gross stuff in the bathrooms. Someone also pooped in an aisle once.
- People who would open food (to try it I guess) and then put it back.
- Lots of arguments with customers over the fact that cigarettes are not a WIC/Food Stamp item.
I think the story that stands out the most to me was this one dude that was moderately creepy. The location I worked at was right next to a huge call center, so most of the daily customers were workers from there.
This one guy would come in two-three times a day to purchase large amounts of junk food. He made a point to only check out with female employees. He was friendly, in that douchey/flirty kind of way. He would usually try to start a conversation with whoever he was checking out with, and continue to talk to you while you rang up other customers.
I think the worst part about him was how he was always trying to share his food with us. So incredibly pushy, and would get incredibly offended if you didn't take him up on his offer.