rudds urdds rduds druds udrds durds rudds urdds rduds druds udrds durds rddus drdus rddus drdus ddrus ddrus uddrs dudrs uddrs dudrs ddurs ddurs rudsd urdsd rdusd drusd udrsd dursd rusdd ursdd rsudd srudd usrdd surdd rdsud drsud rsdud srdud dsrud sdrud udsrd dusrd usdrd sudrd dsurd sdurd rudsd urdsd rdusd drusd udrsd dursd rusdd ursdd rsudd srudd usrdd surdd rdsud drsud rsdud srdud dsrud sdrud udsrd dusrd usdrd sudrd dsurd sdurd rddsu drdsu rddsu drdsu ddrsu ddrsu rdsdu drsdu rsddu srddu dsrdu sdrdu rdsdu drsdu rsddu srddu dsrdu sdrdu ddsru ddsru dsdru sddru dsdru sddru uddsr dudsr uddsr dudsr ddusr ddusr udsdr dusdr usddr suddr dsudr sdudr udsdr dusdr usddr suddr dsudr sdudr ddsur ddsur dsdur sddur dsdur sddur
Note: these 'words' (valid or invalid) are all the permutations of the word rudds. These words are obtained by scrambling the letters in rudds.