wdfu dwfu wfdu fwdu dfwu fdwu wduf dwuf wudf uwdf duwf udwf wfud fwud wufd uwfd fuwd ufwd dfuw fduw dufw udfw fudw ufdw
Note: these 'words' (valid or invalid) are all the permutations of the word wdfu. These words are obtained by scrambling the letters in wdfu.