What's the worst thing you've done in a restaurant as a worker or a guest?

About a year ago I was serving a party of 4 or so in a commonly known chain restaurant. There were four adults and four younger kids at this table who were, for a lack of a better word, white trash. Their kids were throwing shit everywhere, grabbing onto me, knocking over the salt and pepper shakers, dismantling the caddies, etc. All the while the "parents" (who by the way were SPLITTING a coke) acted like it was normal.

One of the women proceeds to order a burger and then sent it back because the burger wasn't cooked the right temperature (which is was, she was just looking for a free meal). My QA has a new one cooked and puts it on a plate, when he turns around to hand it to me the burger patty slips off the plate and onto the floor of the kitchen. To those who haven't worked in a restaurant, know that the kitchen floor is disgusting. I gave my QA the run down and proceeded to serve her the floor burger.

TL;DR: Lady got a floor burger. Don't fuck with people who handle your food.