ongf nogf ognf gonf ngof gnof onfg nofg ofng fong nfog fnog ogfn gofn ofgn fogn gfon fgon ngfo gnfo nfgo fngo gfno fgno
Note: these 'words' (valid or invalid) are all the permutations of the word ongf. These words are obtained by scrambling the letters in ongf.