I'd say no, nationalists have no sense of humor when it comes to that abstraction they hold so dear to their heart: the nation. An abstraction, true, but with a hard-to-deny material presence: the nation-state. So, whenever they come across stereotyped images of their beloved nation - negative images, I should stress - nationalists get even more obnoxious. They complain 'the Others' don't understand them (well, how could they, given that they are 'the Others'). They find themselves collectively humiliated and feel the bitter taste of what they do to 'Others': they're lumped together under a label they dislike.
Entropa does just that. A modern art exhibition recently opened in the heart of Europe, it dares to depict Bulgaria through an installation of oriental toilets, France as a continuous complainer, Italy as a collective soccer-obsession and so on, and so forth. Oh, and it dares to skip the UK altogether... My oh my, what courage. Of course, the Bulgarian government gets all offended and presses for an official reaction. Ironically, in so doing, they only play within the boundaries of the stereotype: an oriental (put your Western glasses on, and read 'backward' - apologies for perpetuating the violence yet again) 'nation' with conservative views. Constipated? (Disclaimer: I don't mean to pick on any one in particular, but these are the actors of this story...).
I, for one, would like to congratulate the artist for his resistance, for his wit and for his humor.