swack wsack sawck aswck wasck awsck swcak wscak scwak cswak wcsak cwsak sacwk ascwk scawk csawk acswk caswk wacsk awcsk wcask cwask acwsk cawsk swakc wsakc sawkc aswkc waskc awskc swkac wskac skwac kswac wksac kwsac sakwc askwc skawc ksawc akswc kaswc waksc awksc wkasc kwasc akwsc kawsc swcka wscka scwka cswka wcska cwska swkca wskca skwca kswca wksca kwsca sckwa cskwa skcwa kscwa ckswa kcswa wcksa cwksa wkcsa kwcsa ckwsa kcwsa sackw asckw scakw csakw acskw caskw sakcw askcw skacw ksacw akscw kascw sckaw cskaw skcaw kscaw cksaw kcsaw acksw caksw akcsw kacsw ckasw kcasw wacks awcks wcaks cwaks acwks cawks wakcs awkcs wkacs kwacs akwcs kawcs wckas cwkas wkcas kwcas ckwas kcwas ackws cakws akcws kacws ckaws kcaws
Note: these 'words' (valid or invalid) are all the permutations of the word swack. These words are obtained by scrambling the letters in swack.