ugfk gufk ufgk fugk gfuk fguk ugkf gukf ukgf kugf gkuf kguf ufkg fukg ukfg kufg fkug kfug gfku fgku gkfu kgfu fkgu kfgu
Note: these 'words' (valid or invalid) are all the permutations of the word ugfk. These words are obtained by scrambling the letters in ugfk.