At Wendy's I've always had to deal with idiot customers. The funniest ones are the teenagers, especially this church goup of people. It was closing time and we had a joint restaurant (Wendy's/Tim Hortons) and I ask the kids to move because we need to clean the dining room. After some smart ass remark about being customers and how they come every Friday night, I said "God wants you to get the fuck out of here!" All of them left, and parents called in to complain the next day. Thankfully my boss backed me up on my saying.
Working for Capital One was a pain in the ass, especially since dealing with American customers about their credit card. There were some awesome arguements on the phone. One person threaten to kill me because he has not paid his bill in 209 days and wondered why his credit was so bad.