zfzu fzzu zzfu zzfu fzzu zfzu zfuz fzuz zufz uzfz fuzz ufzz zzuf zzuf zuzf uzzf zuzf uzzf fzuz zfuz fuzz ufzz zufz uzfz
Note: these 'words' (valid or invalid) are all the permutations of the word zfzu. These words are obtained by scrambling the letters in zfzu.