bunk ubnk bnuk nbuk unbk nubk bukn ubkn bkun kbun ukbn kubn bnku nbku bknu kbnu nkbu knbu unkb nukb uknb kunb nkub knub
Note: these 'words' (valid or invalid) are all the permutations of the word bunk. These words are obtained by scrambling the letters in bunk.