One of the most common English mistakes I hear is the replacement of the verb "to be" with the verb "to stay." I'm sure this occurs because, in Portuguese, we can say either eu estava com raiva or eu fiquei com raiva, literally "I was with anger" or "I stayed with anger," or, I was angry; I stayed angry. One can of course stay angry in English, but first one must be angry. And even then the usage doesn't seem natural to me. "Tammy Sue got angry with Tyler for cheating on her with that tramp he met on the Springer show, and she stayed angry, too, I tell you what." To my ear, it sounds very colloquial. My point, though, is that ficar, to stay, expresses duration and, I think, added intensity, in these situations. Also, a common idiom is to say o banco fica nessa rua, "the bank stays on that street." This is silly in English; of course the bank stays on that street--what, will it get up and walk to another?
That's all I got. I'm pooped. I'll leave you with my good friend Monk. I haven't actually watched this video--something's iffy with my internet connection. But I trust that it shows what is advertised, a performance of "I Mean You."