If I go to chic fil a an buy a sandwich and choke on a piece of plastic can I sue ?

Yes, anyone can sue for anything. The issue in your case is whether you can recover any material amount of money. Generally, whether you can recover money depends on whether you have suffered damages. Damages in this case would include medical costs, lost wages, pain and suffering and similar items. If you are writing this, chances are that your damages are nominal and that a lawsuit would not be productive. If you had died or had been hospitalized, or suffered some long-lasting consequence, you (or your heirs) would have a more meaningful claim.