finder

Prov. If you find something, you are entitled to keep it. (This is a children's rhyme and sounds childish when used by adults.) Bill: Hey! How come you're using my fountain pen? Fred: It's mine now. I found it on the floor—finders keepers, losers weepers. Child: That's my hat. You can't have it. Playmate: I found it. Finders keepers.

something that you say when you find something that belongs to someone else and decide you are going to keep it 'Finders keepers,' he said, putting the money away in his pocket.

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.