nbcok bncok ncbok cnbok bcnok cbnok nbock bnock nobck onbck bonck obnck ncobk cnobk nocbk oncbk conbk ocnbk bconk cbonk bocnk obcnk cobnk ocbnk nbcko bncko ncbko cnbko bcnko cbnko nbkco bnkco nkbco knbco bknco kbnco nckbo cnkbo nkcbo kncbo cknbo kcnbo bckno cbkno bkcno kbcno ckbno kcbno nbokc bnokc nobkc onbkc bonkc obnkc nbkoc bnkoc nkboc knboc bknoc kbnoc nokbc onkbc nkobc knobc oknbc konbc boknc obknc bkonc kbonc okbnc kobnc ncokb cnokb nockb onckb conkb ocnkb nckob cnkob nkcob kncob cknob kcnob nokcb onkcb nkocb knocb okncb koncb coknb ocknb ckonb kconb okcnb kocnb bcokn cbokn bockn obckn cobkn ocbkn bckon cbkon bkcon kbcon ckbon kcbon bokcn obkcn bkocn kbocn okbcn kobcn cokbn ockbn ckobn kcobn okcbn kocbn
Note: these 'words' (valid or invalid) are all the permutations of the word nbcok. These words are obtained by scrambling the letters in nbcok.