I think that many people don't even know that "meuf" is verlan for "femme" (or "keuf" for flic). At least, I didn't know when I was a kid. It got engrained in the language and people decided to "verlan"-ize it again. Because "meuf" ends with a consonant, you need to add an extra vowel "eu" to make the process work. You end up with "meufeu" which reverses to "feumeu".