nsurf snurf nusrf unsrf sunrf usnrf nsruf snruf nrsuf rnsuf srnuf rsnuf nursf unrsf nrusf rnusf urnsf runsf surnf usrnf srunf rsunf ursnf rusnf nsufr snufr nusfr unsfr sunfr usnfr nsfur snfur nfsur fnsur sfnur fsnur nufsr unfsr nfusr fnusr ufnsr funsr sufnr usfnr sfunr fsunr ufsnr fusnr nsrfu snrfu nrsfu rnsfu srnfu rsnfu nsfru snfru nfsru fnsru sfnru fsnru nrfsu rnfsu nfrsu fnrsu rfnsu frnsu srfnu rsfnu sfrnu fsrnu rfsnu frsnu nurfs unrfs nrufs rnufs urnfs runfs nufrs unfrs nfurs fnurs ufnrs funrs nrfus rnfus nfrus fnrus rfnus frnus urfns rufns ufrns furns rfuns fruns surfn usrfn srufn rsufn ursfn rusfn sufrn usfrn sfurn fsurn ufsrn fusrn srfun rsfun sfrun fsrun rfsun frsun urfsn rufsn ufrsn fursn rfusn frusn
Note: these 'words' (valid or invalid) are all the permutations of the word nsurf. These words are obtained by scrambling the letters in nsurf.