bought the younger sister a phrasebook a few years ago devoted to insulting phrases - had several dozen, all ready translated into six or seven languages ready for use no matter where you were.
the standout one had to be 'Oh dear, I appear to have trodden in something unpleasant. Oh, it seems to be your country.'
You can always use the only fully international recognised everywhere phrase.
Said properly this is recognised in all countries and cultures of the world, there are bushmen in the jungles off Borneo who have never even seen a white person and even they get the point when they hear it.