Pretty much anyone who has grown up in the US knows “finders, keepers, losers, weepers”, an expression that alludes to an ancient Roman law (usucapio) describing ‘adverse possession’.
Tonight, while watching a Brazilian flick, I heard a phrase in Portuguese which is the equivalent. It says ‘achado não é roubado‘ (found isn’t stolen). These are the things that make you Brazilian, knowing little phrases off the top of your head like this. In order, I’d say there’s formal language, informal language, cultural references then adages or sayings. Once you have those four down, you’re golden.
Edit: Thanks to Fábio, I now know the rest of the phrase (which I actually heard in the film I saw but didn’t understand that it was part of the phrase). The full phrase is “achado não é roubado, quem perdeu foi relaxado” (found isn’t stolen, the loser was relaxed…or put at ease). I’m sure ‘relaxed’ is only used for rhyming purposes, although I saw as alternatives ‘assaltado’, ‘azarado’ and ‘descuidado’ used while doing some extra research.