Both were concerned with some of the same things. Tropicalia was a artistic, musical, literary, and political movement in Brazil during the sixties and seventies that sought to recast the Brazillian social struggle in new terms, NSK, or Neue Slovenische Kunst, is a movement in the former Yugoslavia, particularly in Slovenia, that started when Yugoslavia was communist, that sought to oppose Communist orthodoxy on political artistic issues. The thread that combines the two is a hatred of nationalism and the conservative Communist orthodoxy that presents a version of what peasant farmers and workers should be that is filled with rhetorical excess, has a tenuous connection to reality, and ultimately serves to enforce a cultural conservatism that can at times border on the fascistic. Some people have called this tendency Communist Neo-Traditionalism.
It really started with Stalin. While Stalin was denouncing everyone as having bourgeois concepts and sending them to their deaths on that basis the progressive social reforms of the early Soviet Union were speedily being drawn back, leading to an idea of the worker as a nationalistic being, with a variant of Soviet nationalism being called "Class consciousness", so technically a Class Conscious person, who had good family values and would have gone to church regularly if religion had ben allowed during Stalin's time. These values, of course, are the real bourgeois values, with nationalism and conservatism based on nationalism being the bourgeois value par excellance.
The way that Class Consciousness became ultra-conservati9sm is easy to see by taking a look at the U.S. There's always a parallel to this sort of thing in the mainstream labor movement, something that Fox News has mightily capitalized on, recasting workers as really being anti-liberal people who wave the flag and support Bush, while liking Christianity a lot. I grew up in the Detroit area, in working class suburbs for most of my life there, and so I know that there's an element of truth to this, but I also know that this sort of thing is inherently oppressive and limiting to people who see the older folks belief in God and Country as being hypocritical, and as opening people up to corruption. Union speeches where people praise family values often go along with the speakers and leaders lining their pockets with members' dues.
In Brazil, the Tropicalia people decided to break out of this stereotype, which is only half true anyways, and look at people as they really are, not just virtuous farmers but as people who for instance like Coca-Cola, and who have identities that aren't subsumed in this greater concept or stereotype. Caetano Veloso, one of the main participants, referred to this as the "Death of Populism" and pointed out Brazilian filmmaker Glauber Rocha's attempts to portray social reality in Brazil using non-traditional methods, often critical of Communist orthodoxy, as being accomplishments in this vein. So the Tropicalistas wrote songs about rich and poor in Brazil, and about the relationship between Brazil and the United States, especially about the U.S.' cultural appropriation of a form of Bossa Nova music and Brazillian dance as being a new form of exoticism, while also implicitly questioning the right-wing government's praising of God and country in the process. But they did it through poetic means that incorporated aspects of European philosophy and the international popular culture emerging during that period, things that Communists no doubt condemned as being bourgeois indulgences.
The Bolsheviks before Stalin would have partially turned the focus in the other direction, criticizing Stalin for bourgeois tendencies himself, something that usefully lives on in certain variations of Trotskyism.
NSK faced a slightly different situation. They lived in the most liberal Communist country, a place where art itself was relatively liberalized in certain areas and where progressive Marxist philosophy flourished. Yet the sense that the NSK people had was that a lot of the positive features of Yugoslavia, like the devolution of power to workers' councils and the putative smaller part that the Communist League, the federation of the party in the different component republics, played in public life, was being taken advantage of by the bureaucracy and was being used to create a new sort of bourgeois nationalism based on the rareness of these features. They pointed out the errors in how the partisan struggle against fascism during the second world war was being portrayed and put to effect as a uniting national myth, not that the struggle wasn't good or succesful, but it had become politicized. You can see some of this in Emir Kusturica's movie "Underground", where one of a pair of bumbling, fun loving, Communists during the partisan struggle is subsequently lionized by the other as being a hero of Yugoslavia, even though the picture painted has absolutely nothing to do with the reality of how this guy was.
While Tropicalia never seems to have gone over the top in directly attacking the military dictatorship in Brazil, NSK through the band "Laibach" went all the way in fusing ultra-Communist and ultra-Fascist imagery in their performances in order to make a statement about all these things.
* on edit: this is where my idea of a neo-romanticism for the United States, plus an American Tropicalia, as well as the criticism of Totalitarian forms of government and society come from. Romanticism in the political sense was itself identified heavily with a rebirth of nationalism in continental Europe, but that's not the sense that I use the term. The Romantics and the Idealists were also the people who first criticized the universiality of Enlightenment political thought, which you remember gave birth to among other things Robespierre's Reign of Terror in the late French Revolution. Looking at the United States now there's the same sort of hypocrisy regarding the origin of our country, where people who harp on it claiming to be concerned with freedom and liberty but in actuality advocating their opposite, using the idea of the American "Founding Fathers" to justify inequality and suppression of civil liberties. This is something that didn't just start after 9/11, either. We're stuck, in a way, in a cul-de-sac of nationalistic bourgeois liberalism and need, if this country is ever going to improve itself, to get beyond this and into new conceptions of how society can be ordered.
Enter the critique of American political ideology, and of our cultural attitudes in general, associated with my idea of Neo-Romanticism and of American Tropicalia.