Wikipedia informs:

Verlan is a type of jargon in the French language, featuring inversion of syllables in a word, and is common in slang and youth language. […] Some verlan words, such as meuf, have become so commonplace that they have been included in the Petit Larousse. Like any slang, the purpose of verlan is to create a somewhat secret language that only its speakers can understand. Words becoming mainstream is counterproductive. As a result, such newly common words are re-verlanised: reversed a second time. The common meuf became feumeu; similarly, the verlan word beur, derived from arabe, has become accepted into popular culture such that it has been re-verlanised to yield rebeu.