“Faça isso não.”
This is yet another linguistic quirk in Brazilian Portuguese, which I like to call the inverted negative fake-out. When Brazilians are telling you something in the negative, they won’t always put the “não” up front, to the extent that it comes almost as a psych-out. “Pode sentar lá não.” For the first 75% of that sentence, you’re led on in the vain hope that you can, in fact, sit over there; then comes the sting of rejection. It is, and I say this with the utmost affection, like Borat trying to learn how to be sarcastic. This shop is abertanão; that bus passanão; this suit is blacknot.
My posts about language have been somewhat controversial (and I say that having written actually controversial things). Either readers are amused (intended effect) or offended, or believe that I am seriously obtuse (also possible) and then send me long emails trying to explain that “tudo bem” is an idiomatic phrase and that it’s not literal and if I need help with Portuguese grammar they would be happy to give me lessons (seriously). Considering starting off every post with some sort of subtle signal that humor is being employed. Another possibility: just ending every commentary with a big LOL JK.
Given all that, I’d like to revisit my thoughts on “tudo bem,” given that they were divulged quite widely. The thing that really struck me about “Tudo bem” – and I didn’t realize that I hadn’t articulated this until interrogated by a carioca – is that it presupposes the answer. It’s not “How are you” or “Qué tal”; it’s “Everything good?” To answer otherwise is to throw off the querent. When you ask “How are you?” you can expect a weary “Fine” or “Okay”; in Toledo the answer to “Qué tal” at our 9 a.m. class was almost invariably “Cansado”; but cariocas expect you to be bem, sempre. Let’s be real: nobody expects an actual answer to “How are you?”, but at least the question pretends to be open-ended. Here it’s tudo bem 24/7, and when it’s not, it’s because you haven’t been to the beach recently enough. LOL JK
ruiva no rio 
I was just talking with a German about how put off she was by the American imperative to ask “How are you?” whenever you encounter someone, to which you must, unless you are intimate, reply, “good.” She felt it was insincere. She thought it would be better to just replace it with hello.
I wonder what would happen if you started saying, “Everything bad?”
LOL JK