The web page URL says it all:
http://krant28.wordpress.com/2008/06/24/top-ten-worst-customers-of-all-time/#comment-5.

1. I had a woman come in one day that wanted to buy a 20 oz. coke ($1.50) with a hundred dollar bill. I told her I didn’t have change and she threw a fit. She said, “You been here ALL DAY LONG and you DON’T have change????? What kind of a clerk are you??? You need to get with the program!!!!” I looked at her like she was crazy (because she was) and I was like, “This is NOT a bank and I don’t OWE you change for a hundred!”

2. One Saturday, shortly after I came on shift, I had a flock of Mexicans come in. They ALL had 100 dollar bills and I had no change, so when the first one came up with 4 bucks worth of stuff, I told him that he was out of luck. This white SOB starts running his mouth about how I should have change for whatever people want. I looked at him like he was idiot and he says, “Don’t look at me like that!”. I was like, “This is my store and I will look at you however I want!” He kept talking junk every time he came in. The second time I was ready to tear his head off his shoulders. I finally had to ban him from the store outright.