1. an expression used in Brazil to describe someone who is clueless, sometimes cheeky and that has absolutely no respect whatsoever for the rules that govern life in society.
2. alternatively, the expression can be used in a more positive way, when the absence of norms is actually more than welcomed! As such, the expression can be used to describe a party that is so insanely out of control, you begin to regret that you're probably too drunk to remember anything the next morning!!!
-Man: a real man should admit his fears, a real woman should know how to cook!
Women all over the world: This guy is completely "sem noçao"!
-Woman in a nightclub: "hey you, you wanna to go to the bar, get something to drink?
Man: What? You want me to pay for your drink or something? Listen woman, I don't have to pay for affection!
Later on, woman to her friends: .... Oh...my...God.. I should have totally made out with that guy, he was so "sem noçao"! "
-Man calls his friend during carnival:
"Dude, last night was completely "sem noçao", I had caipirinhas in my veins, I almost got in a fight with a midget, I started dancing on a barrel in a weird bar, a hot cougar ripped my shirt open and stole my hat, I maxed out my credit card, I sexted all the contacts in my cellphone and I woke up with nail scratches on my back and dollar bills all around my boxer shorts! wait, this isn't my hotel room!?!? "