So what does it mean, "sem lenço e sem documento"?

https://www.youtube.com/watch?v=hmK9GylXRh0

http://letras.mus.br/caetano-veloso/43867/

If you translate this word by word, it would mean “going out without a handkerchief or your driver’s license.

That probably would not make sense to any English speaker. You've got understand what is behind this expression. It means going out without any planning, on the spur of the moment. It also has another meaning in the context the song I had used as an example was written.  During the sixties, Brazil was under a very repressive military regime and many songs had a political message, a sort of disguised protest. So Caetano cleverly plays with the words, because back then going out without your ID meant you could be arrested randomly, and even be accused of being a “subversive”. Torture was a common way to quiet down the unruly youth…many people were sent to jail, and many others went missing. So if you do want know more about Brazilian culture, an the Portuguese language, please contact me.

Eliane