A child who finds something and doesn't want to give it back will say "finders keepers losers weepers". Example: "I found it, it's mine." Reply: "That's not yours, it's mine." Reply: "Finders keepers, losers weepers!"

"Finders keepers losers weepers" says: the natural law of ownership should allow the one who found the thing to be the one who keeps it.

The one who finds the thing (the "finder") wants to keep that thing (and be the "keeper"). The one who loses the thing is sad and crying ("weeping") so he is the "weeper". "Finders keepers losers weepers" is used by children who find things and want to keep those things they find.