serks esrks sreks rseks ersks resks sekrs eskrs skers ksers eksrs kesrs srkes rskes skres ksres rkses krses erkss rekss ekrss kerss rkess kress sersk esrsk sresk rsesk erssk ressk sesrk essrk sserk sserk essrk sesrk srsek rssek ssrek ssrek rssek srsek erssk ressk esrsk sersk rsesk sresk seksr esksr skesr ksesr ekssr kessr seskr esskr ssekr ssekr esskr seskr skser ksser ssker ssker ksser skser ekssr kessr esksr seksr ksesr skesr srkse rskse skrse ksrse rksse krsse srske rsske ssrke ssrke rsske srske sksre kssre sskre sskre kssre sksre rksse krsse rskse srkse ksrse skrse erkss rekss ekrss kerss rkess kress ersks resks esrks serks rseks sreks eksrs kesrs eskrs sekrs ksers skers rkses krses rskes srkes ksres skres
Note: these 'words' (valid or invalid) are all the permutations of the word serks. These words are obtained by scrambling the letters in serks.