The value of knowing one anothers language is vital, that is uncontested. Especially in diplomacy.
But to truly exploit language to its full extent you need to dig deeper. If you use someones language, they will be impressed. If you use their expressions, they will be extactic.
Below are a few expressions we use in Portuguese and their direct translations in english and how they are used:
Estás aqui estás ali! = You are here you are there!
(Used to express annoyance)
Quem não arrisca não petisca = Who doesnt risk, doesnt eat
(Used to express that the bold usually gain the most!)
Estou a falar para o boneco = Im speaking to the doll (Used when someone isnt listening to you)
Muitos anos a virar frangos = Many years turning chickens
(When you have a lot of experience doing something)
Nem fode nem sai de cima = Doesnt fuck and doesnt get out
(Usually used when someone is doing something you want to do and doesnt let/allow you to do it (usually not on purpose))
Zangam-se as comadres, descobrem-se as verdades = The friends get upset, the truths come out
(self explanatory)
Desenmerda-te = Unshit yourself
(Use to tell someone to figure the situation out by themselves)
I will be back with more <3
Leave other expressions in the comments and if you are from another country, teach us some!