Wow, they probably fuck with your food a LOT. I can honestly say that if I was a waiter, and there was a person that always came in, and never tipped, I would fuck with their stuff. As a card dealer, someone who lives off of tips, I can honestly say that no matter how bad the service, I always leave a good tip. The person could be having a really really bad day, but can't even afford to take a day off. When I'm having a really shitty day at work, and someone is extra nice and tips me, I feel quite a bit better. So I try to do the same for others. Hell, I tipped a gas station cashier $5 for cashing in like 15 lotto scratchers I had not too long ago.