Arabs are often referred as beur or reubeu in France. The latter is a term that I recently encountered. Both terms are derived from Verlan, a French slang akin to piglatin. The word verlan itself is derived from the French word l’envers , backwards.
As for verlan, well, it’s verlan: backwards slang for the word l’envers, which means backwards. To make a word in verlan, you cut the original word in two (or three) and put the last syllable first and first syllable last (if there’s a third or fourth syllable, they go in the middle).
Verlan’s been around since at least the 1930s – some say much longer, and they’re probably right – but started becoming popular in the 1970s. It began in the Paris suburbs – mostly in the housing projects inhabited by low income, and often immigrant families (called les cités, or técis in verlan). So a lot of the first words in backwards slang were the ones being used by teenagers in the projects, often relating to drugs, sex and crime and, like a lot of slang, meant to be incomprehensible to outsiders. In the 80s and 90s, verlan was a mainstay of early French rap. (Say what you will; some of it is downright kyfun.)
So, in verlan a rotten (pourri) cop is called a ripou, an Arab is a beur (and flipped again to become a robeu), a Frenchman becomes a céfran, une femme (woman) a meuf, fête becomes teuf, vas-y (go!) is zyva, and barjot (slang, originally meaning naïve & bourgeois, later signifying just plain crazy) becomes the spit-collecting word jobard.
Let’s start with the word l’envers, which means the reverse. Separate l’envers into its two syllables l’en and vers. Invert them, put them together into a single word, and then adjust the spelling:
l’envers… l’en vers… vers l’en… versl’en… verslen… verlen… verlan
Arabe… a ra beu… beu ra a… beura… beur
For example, arabe becomes beur, which in turn becomes reubeu