If the diner(s) just don't have enough money to cover the bill, the manager could call the police. I suppose it could be considered a larceny, and/or fraudulently obtaining goods/services. I would hope that it wouldn't come to that. Although, I have never heard of anyone required to do dishes to compensate the restaurant for the food they ate (a la "I Love Lucy"), I suppose one could do that too.
The restaurant manager would probably ask for your credit card. However, if you don't have one, or if the restaurant doesn't take credit cards, the manager would probably have you leave your name and address (proved by your current driver's license) and phone number so that they have your information in order to file a criminal complaint if you don't pay by an agreed upon date.
If the person had a guest, one or the other might stay at the restaurant, nursing a cup of coffee or tea, while the other quickly runs to the nearest ATM!! (This actually happened to my husband and I when we were dating. The restaurant didn't take credit cards, so I ordered dessert and coffee to buy time for my husband to RUN to the ATM machine down the block. It was pretty embarrassing, but the dessert was fabulous!)