to be out of the loop, to be clueless
Você não sabia que eles terminaram? Nossa, você está por fora!
You didn't know they broke up? Wow, you are so out of the loop!
The image is spatial: to be por fora is to be "on the outside" — outside the circle where things are known and discussed, and therefore out of the loop and uninformed. It is informal Brazilian slang, the natural opposite of being por dentro ("on the inside," in the know), and its origin lies in this everyday metaphor rather than in any single documented episode.
Falando's Idiom Trainer teaches you to recognize idiom meanings and create sentences using them, so you can speak like a Brazilian.
