nbox bnox nobx onbx bonx obnx nbxo bnxo nxbo xnbo bxno xbno noxb onxb nxob xnob oxnb xonb boxn obxn bxon xbon oxbn xobn
Note: these 'words' (valid or invalid) are all the permutations of the word nbox. These words are obtained by scrambling the letters in nbox.