SUBREDDIT: r/AskReddit
TITLE: Servers of reddit, what is the most ridiculous justification people have used in order to stiff you on a tip or get free food?
POST: I don't work in the food service industry, but several of my friends do, and they tell me it is hell. 

My buddy told me a story about a family of five who came in to the pizza joint he worked at and ordered several pizzas. When they were served, the patrons told the server everything was fine, ate one piece of each pizza, and complained that they were all wrong. They sent the pizzas back, got several more, ate a few slices each, and the order was "wrong" again.

They managed to walk out with an incredibly reduced bill and didn't pay a tip because of the lack of "quality service."
I could take this on a larger rant about how ridiculous it is that servers/restaurant owners have to put up with blatant shit like this, but I'm curious about your stories.
TL;DR: 
Family acts like assholes, gets free pizza. What's your story about ridiculous ways people got reduced bills, free food, or refused to tip because of some made-up reason?