Quite enjoying a little nugget of dialogue I saw yesterday:
Posso means “may I?” and you probably know it’s used like “excuse me”, just as it is in English. If you need to squeeze past someone in a crowded space, you can say “posso” – may I? But since it is basically a question, the person you say it too might answer with the same verb in the second person and build it out a bit: “podes mas não deves”. You may, but you shouldn’t. It’s a kind of banterish way of replying if you are a banterish kind of person. Not quite as aggressive as this scene, which is the closest thing I can think of in English.