Nickels...next crappy shift at BWW, here's some stories to restore your faith in humanity:
http://kitchenette.jezebel.com/stories-of-the-best-and-funniest-restaurant-customers-1741363951
I have nice tables that usually balance out the bad ones, the bad ones just have tendency to stick out more. I don't think people think about how long they take up a table when they are watching a game. Someone sitting there for several hours and leaving a 10% (or worse) tip is going to upset the server more than usual. Normally that table would have been turned 3-4 times during that same time span.