Honestly, no matter how rude or weird they are being, as a server, think to yourself, "What is the easiest solution to this problem?" If they don't like their meal, offer to take it back and get something else. If they think their food is taking too long, politely explain that sometimes the kitchen gets backed up. Even if they are completely out of line, you have to suck it up and try to fix the problem. When a guest is really upset, I always get the manager. Customers - you have to remember, it's just dining out, not a life or death matter. Relax, enjoy your food and company. In the scheme of things, your burger is not THAT important!