rucks urcks rcuks cruks ucrks curks rukcs urkcs rkucs krucs ukrcs kurcs rckus crkus rkcus krcus ckrus kcrus uckrs cukrs ukcrs kucrs ckurs kcurs rucsk urcsk rcusk crusk ucrsk cursk rusck ursck rsuck sruck usrck surck rcsuk crsuk rscuk srcuk csruk scruk ucsrk cusrk uscrk sucrk csurk scurk ruksc urksc rkusc krusc ukrsc kursc ruskc urskc rsukc srukc usrkc surkc rksuc krsuc rskuc srkuc ksruc skruc uksrc kusrc uskrc sukrc ksurc skurc rcksu crksu rkcsu krcsu ckrsu kcrsu rcsku crsku rscku srcku csrku scrku rkscu krscu rskcu srkcu ksrcu skrcu cksru kcsru cskru sckru kscru skcru ucksr cuksr ukcsr kucsr ckusr kcusr ucskr cuskr usckr suckr csukr scukr ukscr kuscr uskcr sukcr ksucr skucr cksur kcsur cskur sckur kscur skcur
Note: these 'words' (valid or invalid) are all the permutations of the word rucks. These words are obtained by scrambling the letters in rucks.