Idioms and Phrases with finders, keepers
A phrase meaning that whoever finds something is entitled to keep it. For example, Someone left a dollar bill in this rented car—finders, keepers. This expression alludes to an ancient Roman law to that effect and has been stated in numerous different ways over the centuries. The modern version, often stated as Finders keepers, losers weepers, dates from the mid-1800s and is no longer a legal precept.