Be their food vendor and require payment up front.  2/3s of their food expenditures will be used keep up the waitstaff's sugahs and compensating angry patrons for the shitty service.  You really expect a fat server to stay on her feet for more than two minutes at a time? Don't be their lawyer.  They'll be up to their eyeballs in lawsuits from hygiene and food safety violations.  And don't be their health insurer, either.  Beetus, anyone?