drubs rdubs durbs udrbs rudbs urdbs drbus rdbus dbrus bdrus rbdus brdus dubrs udbrs dburs bdurs ubdrs budrs rubds urbds rbuds bruds ubrds burds drusb rdusb dursb udrsb rudsb urdsb drsub rdsub dsrub sdrub rsdub srdub dusrb udsrb dsurb sdurb usdrb sudrb rusdb ursdb rsudb srudb usrdb surdb drbsu rdbsu dbrsu bdrsu rbdsu brdsu drsbu rdsbu dsrbu sdrbu rsdbu srdbu dbsru bdsru dsbru sdbru bsdru sbdru rbsdu brsdu rsbdu srbdu bsrdu sbrdu dubsr udbsr dbusr bdusr ubdsr budsr dusbr udsbr dsubr sdubr usdbr sudbr dbsur bdsur dsbur sdbur bsdur sbdur ubsdr busdr usbdr subdr bsudr sbudr rubsd urbsd rbusd brusd ubrsd bursd rusbd ursbd rsubd srubd usrbd surbd rbsud brsud rsbud srbud bsrud sbrud ubsrd busrd usbrd subrd bsurd sburd
Note: these 'words' (valid or invalid) are all the permutations of the word drubs. These words are obtained by scrambling the letters in drubs.