It is illegal to annoy others by slurping your soup in a public diner.

The Law Explained

Stemming from older public nuisance and disturbing the peace statutes, making aggressively loud noises while consuming soup or liquids was once cited as an actionable offense. Designed to maintain decorum in crowded urban eateries and train stations, it speaks to an era where dining etiquette was strictly enforced by local constables.