Different cultures insult in different ways. Things that would offend one culture are just not that big of a deal for another. Folks who've studied Monty Python know that French people insult invading English k'niggets by saying that their mothers were hamsters and their fathers smelt of elderberries.
The folks at the Just the Flight travel blog have compiled a handy infographic showing some insults you might hear when traveling, as well as the way the phrase sounds in its original non-English language. Many of them are highly entertaining. In Bulgaria, for example, should a local direct the phrase "Grozna ni kato salata" at you, he or she is saying you are as "ugly as a salad." I am not certain how the conversation with a Bulgarian would go after this, because I would probably be laughing instead of being insulted.
I am not sure of the actual insult content of some of the entries. Australians may indeed call someone with red hair a "'ranga," referring to the red-haired great ape the orangutan. But how is it insulting to be called red-headed?
And some provoke some interesting images. "Gå och dra något gammalt över dig," a Swedish person might say to you should you say or do something stupid: "Go and hide under something old." ("That explains all the Swedes under my chair," Bernie Sanders was heard to comment. "No kidding," responded Cher.)
A Russian might say of you, "Hot' kop na gopove teshi," which means, "You could sharpen an axe on the top of his head." The phrase implies a person is stubborn; it is not meant to be taken literally. ("Oops," said Vladimir Putin.)
The Irish seem to have our current political landscape well mapped out with the phrase, "As thick as manure and half as useful." The applicability seems clear. Unfortunately, we are stuck with those fitting that description, as much as we might want to confront the existing crop of candidates with the Somali phrase "Futaada u sheeg."