Flatfoot's Collar is a term used to describe a police officer's badge. It is a symbol of authority and is worn by police officers to signify their role in law enforcement. The term 'FLATFOOT's collar' is derived from the shape of the badge, which is usually round or oval with a flat bottom. The term is also used to refer to the act of arresting someone, as the badge is a sign of the officer's authority to do so.