lkur klur lukr ulkr kulr uklr lkru klru lrku rlku krlu rklu lurk ulrk lruk rluk urlk rulk kurl ukrl krul rkul urkl rukl
Note: these 'words' (valid or invalid) are all the permutations of the word lkur. These words are obtained by scrambling the letters in lkur.